Mindri0t

the truck is a '01 5.3L LS with an automatic transmission. Basically every now and then (doesn't happen every time) I will be on the highway at about 50mph and push the throttle down 3/4 of the way, and the tranny downshifts and won't lockup right away, infact it won't lock, then it locks then it won't lock until I let off the gas pedal. Driving it around town it does fine, wide open throttle does fine. The shift from 1st to 2nd gear is awful harsh all the time, almost feels like the rear end slips a bit as it shifts into second. So my question is, is my tranny toast, or is it just a lockup problem and how can I check to see? the truck only has 40,000 miles. I appreciate any advice as this problem is a real headache.

I beleive limited slip is what I am after, I just want both tires to lock in a straight line. I appreciate the feedback you guys rock! Any suggestions on the gear ratio I should look for? I would like a little more umph on take off but I still need highway speeds at reasonable rpms.

I currently have a 2001 Silverado with the 5.3L and it has I beleive a 3.23 open differential, I have never torn into a rearend before and was wondering if they sell a kit to make it full time posi?