rear end noise when turning corners

[bucktruck]

I've got a 94 Astro EXT AWD. I was having an issue with what I thought was the rear-end knocking as I turned corners. So, I got a bone-yard rear end and planed to do a swap. I got my rear end out, and took the cover off to make sure I had the same gears, and noticed that my rear end looked better than the boneyard one I got. The oil looks clean, and there were no metal shavings or anything in it, and the axle seals aren't leaking at all, and there is very little play at the axles.
So, I'm afraid either it wasn't my rear end making the noise, and it something else, or, the boneyard rear-end I got is in just as bad of shape as mine and will have the same problems if I swap it out. I've had my van for about 3yrs and just started making the noise this summer. the van has about 140k miles on it.
Does anybody have any suggestions before I put either of these rear-ends back in the van and have the same problem?
Oh, its a non-posi, 2.73 rear end as well.
Thanks for any help.

[WoodButcher]

Use the better of the two even if it's the original and if you still hear the knock start looking for it again. Have someone else drive so you can find the noise. I've never known a rear axle to make a knock, look at the spring mounts and shocks, exhaust pipe and muffler. were the clamshells and U-bolts all good?

[snapper388]

last time I had a popping noise while turning the tire store left the lug nuts loose.

[bucktruck]

Now that you mention, the exhaust tailpipe was loose. I think I'm going to put my original one back in and see what happens. Guess I shouldn't have been so quick to assume it was the rear end. Might have saved myself a lot of trouble.

[chevymaher]

Look at the shocks to. When the bushins go bad the shock smacks on the rear end.

[bucktruck]

I know this is now a few years old, but I thought I would post an update in case someone else is doing a search for the same problem.
It turned out it was the front U-joints. I put the original rear-end back in. Unfortunately, I couldn't get just the u-joints, I had to buy the whole drive shaft assembly, so it was about $500 to get it fixed. But, well worth it.

[97cargocrawler]

*****! Thanks for letting us and future generations know.