Cheryl Schatz

Craig,
The Textus Receptus which corresponds to the KJV shows submission but the NA27 (Nestle Aland Greek New Testament) has mutual humility rather than submission.

However the humility is akin to submission since verse 6 shows that mutual humility is placing ourselves under God in a lowered position so mutual humility (verse 5) is placing ourselves in a lowered position towards each other.

1 Peter 5:5–6 (NASB95)
5You younger men, likewise, be subject to your elders; and all of you, clothe yourselves with humility toward one another, for GOD IS OPPOSED TO THE PROUD, BUT GIVES GRACE TO THE HUMBLE.
6Therefore humble yourselves under the mighty hand of God, that He may exalt you at the proper time,

Also the term “likewise” in verse 5 connects the submission in verse 5 to the service of elders in 1 Peter 5:2, 3. Elders are to voluntarily or willing shepherd the flock but not with any intention of lording over the flock but as a service to the flock in willingly protecting them. The mutual humility shows mutual service putting oneself under the other for the purpose of service so that the others are treated as if they are first and you are to receive the last place.

Thus with the mutual submission of the NASB and mutual submission of the NKJV, the idea is the same in both with deliberate mutuality.

Does this help?