Re: Drivetran help! Th-Thunk
Either way, pull the diff cover off and check the condition of what you have before you do anything.
If it's just the pinion nut that's loose like Sandman had, just disconnect the rear driveshaft from the axle and tighten it back down (maybe use some Lok-Tite on it). I don't remember the exact torque spec, but it's somewhere around 150 ft-lb. Hopefully the pinion bearings aren't shot and the gears aren't blown apart (see Sandman's post for a fine example of blown apart gears [img]/wwwthreads_images/icons/wink.gif[/img]).
If the problem lies in the rod that goes through the spider gears like on my `82 Blazer axle, jack up the back of the truck, pull the diff cover off and check to see if the rod is bent. If you pull the little retaining screw out, the pin should slide right out if it's alright, if you have to pound on it, it's bent and you'll need a new one. If you do pull the pin out, push in on the axleshafts (tires, wheels) and check to see if the C-clip retainers are in good condition.
Swapping a REAR axle is not hard at all. If you go this route, <font color=red>be absolutely sure you get a replacement axle with the same gear ratio!</font color=red> All an axle swap requires is cutting 4 u-bolts (torch), disconnecting rear driveshaft and brakes. Another s-truck axle should be a direct bolt-in (this might be your chance to drop in that 4-wheel disk rear you've always wanted [img]/wwwthreads_images/icons/laugh.gif[/img]). Install and tighten u-bolts, reconnect the brake lines, driveshaft, bleed the brakes, change diff fluid and you're done. I've swapped out a rear axle in a half ton truck in under 2 hours before without help, but I had all the tools needed to do the job.
You should be able to use a 2-wheel or 4-wheel drive rear axle - the wheel bolt patterns are the same. $200 would be a decent price from a junk yard depending on the gear ratio (could be 4.11's with a 2.8L), any less would be a screamin' deal. A posi will run you more. If the junkers want more than $300 for an axle, I'd start looking for a donor truck - buy a truck for the axle, part the rest out and sell the parts; maybe make a little bit of money on top, too.
<font color=red>TOO MUCH POWER</font color=red> isn't enough.