Bluemeanie

Hey All,
I sold my 77 Trans Am W72 4 speed posi car to my brother to help fund purchasing my Olds. It's been living in storage here, while he finished his new garage space in Portland. I'm going to drive it down to him in a couple weeks.
I took the car out last weekend on a long drive to make sure everything was working good. The car ran like a top, except after a long stint (about 30 miles) on the freeway. When I pulled of the exit the RR wheel was clunking, and sounded/felt like the lugs were loose. Scared the crap out of me. Got out, checked the lugs, and felt for a hot wheel, (nothing) then rolled down the road in a 40 zone home for about 10 miles with no problems.
Obviously I'm no diff expert, but can the spider gears bind? What would cause that?? Is it safe to drive? Should I even think about driving it to Portland? I don't really have an extra 1K+ floating around. Hoping you guys can give me some guidance.
Mr. Trick???
I know this is essentially non Olds related, so I appreciate any help.
Thanks!!

Rickman48

I'd change the fluid, and add the posi lube.
Check the u-joints while there.

frankr442

X2 on the fluid change. It made a difference in my case. Blew the diff case in my 71. Pulled the rear end out of a 72, drained, flushed and filled with Castrol + add. Within 10 miles developed a scary knocking noise. Asked to use a friends garage because mine is too narrow to pull the axles. He asked me if I had used the GM fluid.`I intended to go about a 100 miles and then use the expensive GM fluid. To shorten this lenghtening story, the GM fluid 89021671 and 1-1052358 additive got rid of the noise. My friend gave me hell because I'm the GM partsman.

J-(Chicago)

Any noticeable slapping or clunking, tells me it has to come apart. I wouldn't drive it anywhere until you inspect.

Bluemeanie

No doubt I'll open it up and look/new fluid/posi lube,..I obviously just don't know what I'm looking for (unless I see pieces or shavings), just curious if this was a common problem with a common solution or not. Thanks for replys! Wasn't sure if I was going to get any since it's not an Olds. Though it was a donor for the Olds!!!
I'll throw up a post if I find anything, and whatever the result ends up being.
Thanks again...