I Corinthians 1:1x

KJV - Paul, called to be an apostle of Jesus Christ through the will of God, and Sosthenes our brother, (Aleph, A, Byz)

NASV - Paul, called as an apostle of Jesus Christ by the will of God, and Sosthenes our brother, (Aleph, A, Byz)

NIV - ​ Paul, called to be an apostle of Christ Jesus by the will of God, and our brother Sosthenes, (B)

I Corinthians 1:28

KJV - And base things of the world, and things which are despised, hath God chosen, yea, and things which are not, to bring to nought things that are: (B, Byz)

NASV - ​and the base things of the world and the despised God has chosen, the things that are not, so that He may nullify the things that are, (Aleph, A)

NIV - God chose the lowly things of this world and the despised things—and the things that are not—to nullify the things that are, (B, Byz)

I Corinthians 2:4

KJV - And my speech and my preaching was not with enticing words of man's wisdom, but in demonstration of the Spirit and of power: (A, Byz)

NASV - ​and my message and my preaching were not in persuasive words of wisdom, but in demonstration of the Spirit and of power, (Aleph, B)

I Corinthians 3:3

KJV - For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men? (Byz)

NASV - ​for you are still fleshly. For since there is jealousy and strife among you, are you not fleshly, and are you not walking like mere men? (Aleph, A, B)

I Corinthians 3:5

KJV - Who then is Paul, and who is Apollos, but ministers by whom ye believed, even as the Lord gave to every man? (Byz)

NASV - What then is Apollos? And what is Paul? Servants through whom you believed, even as the Lord gave opportunity to each one. (Aleph, A, B)

I Corinthians 4:17

KJV - Wherefore I beseech you, be ye followers of me. For this cause have I sent unto you Timotheus, who is my beloved son, and faithful in the Lord, who shall bring you into remembrance of my ways which be in Christ, as I teach every where in every church. (A, B, Byz)

NASV - ​For this reason I have sent to you Timothy, who is my beloved and faithful child in the Lord, and he will remind you of my ways which are in Christ, just as I teach everywhere in every church. (A, B, Byz)

NIV - For this reason I have sent to you Timothy, my son whom I love, who is faithful in the Lord. He will remind you of my way of life in Christ Jesus, which agrees with what I teach everywhere in every church. (Aleph)

I Corinthians 5:4

KJV - In the name of our Lord Jesus Christ, when ye are gathered together, and my spirit, with the power of our Lord Jesus Christ, (Byz)

NASV - ​In the name of our Lord Jesus, when you are assembled, and I with you in spirit, with the power of our Lord Jesus, (B)

Note: 'Aleph' says "Lord Jesus Christ", omitting "our".
'A' says "Lord Jesus", omitting "our".
In 'Byz', the end of the verse is just like the first - "our Lord Jesus Christ". 
In 'B', the end of the verse is just like the first - "our Lord Jesus". 
The endings of the verse in the other manuscripts are undetermined.

I Corinthians 5:5

KJV - To deliver such an one unto Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus. (Aleph, Byz)

NASV - I have decided to deliver such a one to Satan for the destruction of his flesh, so that his spirit may be saved in the day of the Lord Jesus. (Aleph, Byz)

NIV - hand this man over to Satan for the destruction of the flesh, so that his spirit may be saved on the day of the Lord. (B)

Note: 'A' says "our Lord Jesus Christ".

I Corinthians 6:11

KJV - And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God. (A, Byz)

NASV - ​Such were some of you; but you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus Christ and in the Spirit of our God. (Aleph)

Note: 'B' says "our Lord Jesus Christ".

I Corinthians 6:20

KJV - For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God's. (Byz)

NASV - For you have been bought with a price: therefore glorify God in your body. (Aleph, A, B)

I Corinthians 7:5

KJV - Defraud ye not one the other, except it be with consent for a time, that ye may give yourselves to fasting and prayer; and come together again, that Satan tempt you not for your incontinency. (Byz)

NASV - Stop depriving one another, except by agreement for a time, so that you may devote yourselves to prayer, and come together again so that Satan will not tempt you because of your lack of self-control. (Aleph, A, B)

I Corinthians 7:7

KJV - For I would that all men were even as I myself. But every man hath his proper gift of God, one after this manner, and another after that. (B, Byz)

NASV - ​Yet I wish that all men were even as I myself am. However, each man has his own gift from God, one in this manner, and another in that. (Aleph, A)

I Corinthians 7:34

KJV - There is difference also between a wife and a virgin. The unmarried woman careth for the things of the Lord, that she may be holy both in body and in spirit: but she that is married careth for the things of the world, how she may please her husband. (Byz)

NASV - ​and his interests are divided. The woman who is unmarried, and the virgin, is concerned about the things of the Lord, that she may be holy both in body and spirit; but one who is married is concerned about the things of the world, how she may please her husband. (B)

Note: 'Aleph' and 'A' say "The unmarried woman, and the unmarried virgin,"  "Wife" (Byz) and "woman"(B) are translated from the same Greek word.  "Woman" in the KJV is implied.  The significant variation between the manuscripts is the word order between "unmarried" and "virgin".  The obvious translation disparity results in part from punctuation differences.

I Corinthians 8:7

KJV - Howbeit there is not in every man that knowledge: for some with conscience of the idol unto this hour eat it as a thing offered unto an idol; and their conscience being weak is defiled. (Byz)

NASV - However not all men have this knowledge; but some, being accustomed to the idol until now, eat food as if it were sacrificed to an idol; and their conscience being weak is defiled. (Aleph, A, B)

I Corinthians 9:20

KJV - And unto the Jews I became as a Jew, that I might gain the Jews; to them that are under the law, as under the law, that I might gain them that are under the law; (Byz)

NASV - To the Jews I became as a Jew, so that I might win Jews; to those who are under the Law, as under the Law though not being myself under the Law, so that I might win those who are under the Law; (Aleph, A, B)

I Corinthians 10:9

KJV - Neither let us tempt Christ, as some of them also tempted, and were destroyed of serpents. (Byz)

NASV - ​Nor let us try the Lord, as some of them did, and were destroyed by the serpents. (Aleph, B)

Note: The 'A' manuscript says "try God". The fourth revised edition of "the Greek New Testament" text follows the "Byz" manuscript ("Christ").  NASV translators preferred the "Aleph" / "B" reading.

I Corinthians 10:11

KJV - Now all these things happened unto them for ensamples: and they are written for our admonition, upon whom the ends of the world are come. (Aleph*, Byz)

NASV - ​Now these things happened to them as an example, and they were written for our instruction, upon whom the ends of the ages have come. (A, B)

Note: The 'Aleph' manuscript differs from 'Byz' only in word order. The actual meaning is the same.

I Corinthians 10:24

KJV - Let no man seek his own, but every man another's wealth. (Byz)

NASV - Let no one seek his own good, but that of his neighbor. (other manuscripts)

Note: "Another's wealth" (KJV) and "that of his neighbor" (NASV) are translations from the same Greek phrase.

I Corinthians 10:28

KJV - But if any man say unto you, This is offered in sacrifice unto idols, eat not for his sake that shewed it, and for conscience sake: for the earth is the Lord's, and the fulness thereof: (Byz)

NASV - But if anyone says to you, “This is meat sacrificed to idols,” do not eat it, for the sake of the one who informed you, and for conscience’ sake; (Aleph, A, B)

I Corinthians 11:24

KJV - And when he had given thanks, he brake it, and said, Take, eat: this is my body, which is broken for you: this do in remembrance of me. (Byz)

NASV - ​and when He had given thanks, He broke it and said, “This is My body, which is for you; do this in remembrance of Me.” (Aleph, A, B)

I Corinthians 11:29

KJV - For he that eateth and drinketh unworthily, eateth and drinketh damnation to himself, not discerning the Lord's body. (Byz)

NASV - For he who eats and drinks, eats and drinks judgment to himself if he does not judge the body rightly. (Aleph, A, B)

I Corinthians 13:3

KJV - And though I bestow all my goods to feed the poor, and though I give my body to be burned, and have not charity, it profiteth me nothing. (Byz)

NASV - ​And if I give all my possessions to feed the poor, and if I surrender my body to be burned, but do not have love, it profits me nothing. (Byz)

NIV - If I give all I possess to the poor and give over my body to hardship that I may boast, but do not have love, I gain nothing. (Aleph, A, B)

Note: The variant words are "burned" and "boast".
Some words are translated "give (surrender) my body" in KJV and NASV.
The same words are translated "give over my body to hardship" in NIV.

I Corinthians 13:4

KJV - Charity suffereth long, and is kind; charity envieth not; charity vaunteth not itself, is not puffed up, (Aleph, A, Byz)

NASV - Love is patient, love is kind and is not jealous; love does not brag and is not arrogant, (Aleph, A, Byz)

NIV - Love is patient, love is kind. It does not envy, it does not boast, it is not proud. (B)

I Corinthians 14:38

KJV - But if any man be ignorant, let him be ignorant. (B, Byz)

NASV - ​But if anyone does not recognize this, he is not recognized. (Aleph, A)

I Corinthians 15:10

KJV - But by the grace of God I am what I am: and his grace which was bestowed upon me was not in vain; but I laboured more abundantly than they all: yet not I, but the grace of God which was with me. (A, Byz)

NASV - But by the grace of God I am what I am, and His grace toward me did not prove vain; but I labored even more than all of them, yet not I, but the grace of God with me. (Aleph, B)

NIV - But by the grace of God I am what I am, and his grace to me was not without effect. No, I worked harder than all of them —yet not I, but the grace of God that was with me. (A, Byz)

I Corinthians 15:47

KJV - The first man is of the earth, earthy: the second man is the Lord from heaven. (A, Byz)

NASV - ​The first man is from the earth, earthy; the second man is from heaven. (Aleph, B)

I Corinthians 15:55

KJV - O death, where is thy sting?  O grave, where is thy victory? (Byz)

NASV - O death, where is your victory?  O death, where is your sting?​ (Aleph, B)

Note: The 'A' manuscript says simply "O death, where is thy sting?" The second part is not included.