Rear end squeek

I have a 2005 Z71 Silverodo offroad. I just changed front diff lube, transfer case lube, with GM auto tracII oil, and the rear end lube. Now I have a squeal. As far as I can tell it’s comming from the rear end. The faster you go the higher the pitch of the squeal. It only happens when you give it gas and does not do it in reverse. The possible blunder is I sealed the rearend cover with RTV instead of the gasket. I will check all lube levels and change the rearend lube again. This time I will seal with the gasket. Should I be concerned about having to replace a bearing or something else. Please give me you comments.

I found my own problem. As I was checking the rearend lube I thought to myself while I’m down here let’s drop the drive line. Sure enough a dry U joint at the transfer case and the other one getting ready to go. Thank you all for all your help and all your replys. I love the car guys. Keep up the good work. Andy