About a month or so ago I swapped out my rear axle assembly on my 91 xj with a D44 out of an 89 xj and about a week ago my rearend started makin noise when I'm doing 60+ mph and let off the gas.
It doesn't happen when I'm on the gas, or when I'm slowing down, just that moment when I let off the gas. I do have about 3" of bastard pack lift in the rear. I was hoping it was my U-joint but my dad is telling me that when u-joints go out the pop when going into reverse and drive. Mine does not do this.
Can someone please shed some light on my situation?

 

I have an 89 cherokee and My rearend (dana 35) did the same thing id let off the gas and it would make noise it got worse and worse over about 6 months time to where it did it about all the time. I replaced mine with a cryco 8.25 29 spline rear end from a 2000 XJ best upgrade ive done so far all the noise went away sounds great. not jumping to conclusion but it sounds like its starting to wear out like mine. You could try changing the fluid with a little heavier weight if you didnt do that when you swapped it out.

How many miles were on the dana 44?

what did the fluid look like when you got it?

 

Not sure on the miles. I pulled it apart and the fluid looked great. I tore it all down and checked bearings an installed a Richmond lock right locker. I reused my original drive shaft

 

"my rearend started makin noise when I'm doing 60+ mph and let off the gas."

We are talking about the differential right? The bearings are failing and it will eventually grenade.

If not:

 

Yea that what I'm affraid of