the truck has been in my garage science July 2011 backed in the front is facing out. well this week i put the truck on 4 jack stands and removed all the tires. i took off all 4 drums and just checked the brakes out i didn't mean greasing the breaks i meant just greasing the bearings in the front wheel cylinders. all the brakes were good and all the springs were good, so i put on all 4 wheels and spun them while it was on the jack stands. after that i put transmission fluid in 3 quarts that's what it needed i assume because it was sitting for a while and may have leaked out, then i put the truck in reverse while it was still on the jack stands it went in reverse fine only the RR wheel spun so i assumed it isn't a posi. i tested out the brakes while it was still in reverse and the wheel stopped fine. then i put the truck in drive while it was still on jack stands and the RR wheel spun and stopped fine. so i went in for the night this was Friday, then came back to it after work today (Saturday) tested it one more time it worked so i took the truck off all 4 jack stands and set it down. i started it up put it in drive to drive it out of the garage i got about a foot if that and then the LR wheel locked up it barely spun it squeaked on the garage floor so i put it in reverse it backed up fine, then i went to put it in drive and it moved a little bit and then locked up i tried going forward a little to see if it would break free but it didn't. so i backed it up, back how it was and it went back about 4 feet or so perfectly fine in reverse. the rear has fluid in it i checked. the guy who gave me the truck said it locked up on him before to the last time he drove it about 5 years ago maybe but he said after a block or so it broke free and was fine, and when we towed it to my house the same LR wheel was locked up so im stuck and not too sure what it is. Thanks for the help guys and sorry about my spelling and punctuation.