We had to replace the spider gears and the cross shafts. The Dana 44 Power Lock came in two versions, one with two spider gears and the other with 4 spider gears. The 4 spider gear version is much stronger. The orginal cobras came with 4 spider gears. If you have the two spider gear version I would suggest upgrading to the 4 version or better yet to a Quaiffe. The only bad part about a Quaiffe is the price (about $1,500), however they work great. I am afraid that it is time for you to pull the cover off your diff and look inside and see what is laying in the bottom. At the very least I would drain the fluid and see how much "metal" is in the
oil. Good luck
Tom