I own a 90 f-150 4x4 with e40d. The tranny has recently been rebuilt, and all u joints replaced. When the truck is driven for longer periods of time, and i come to a dead stop then take off, i hear a little clunk, more or less like something is moving underneath the truck that shouldnt, it goes and comes, but always when i have been driving for a while, i do know there is a little bit of play in the rear end, maybe noew rear end? I have the 8.8 w/3.55's, is that expensive, or another thing i heard was the t-case, i have the borg warner 1356, sould something be loose inside to cause this sound??

 

I would suggest something simpler. Your mounts. If it was out, and then put back in, it is possible that things have settled, and are now a little loose. Check the tranny mount, and the idler bearing mount if you have one. Ted

 

Try removing the rear driveshaft and lubing the splines inside the slip yoke where it goes into the transfer case. Ford has Teflon grease for this but you can use any good quality grease. If it fixes it you have the choice of lubing it occasionally or replacing the slip yoke.

 

Would wheel bearing or lithium grease work for this?

 

I've seen people use many types of grease and they all seem to work.