im nbot a gear expert, but to me it sounds like the teeth arent lined up on the inside, like someone stated before

Nope....just straight swap...3:55s out 4:56 in .....with Master Kits

sounds like incorrect backlash. Not enough play in the gears when you let off the gas and the ring and pinion are binding up. in drive your pinion is pushing the ring so it's a non issue, but when you let off the gas, the pattern is so tight that the ring starts to push on the back side of the pinion gear and you get "bucked". getting it towed off the rear axle might save the gears, but only if he didn't do the same to the front. You might be able to drive there very slowly without having to slow down if it's really close, but the best bet would be a full platform tow.

Thank you....I don't know much about setting them up as you can tell and that's why i let someone else do so. What you says makes sense and is more than likely the case...thank you very much!

Finally got to try my truck with the 4:56.....It works amazing.....very impressed. The hopping seemed to smooth out on my way to the garage, The opened the case and checked the backlash and it was inside spec, Changed the oil and sent me on my way. The truck actually has the power to back up the magnaflow dual sound now. Thanks to everyone for the insight....I will post some fresh picks with all my mods and add ons soon....Happy Trucking!

Good to hear that it's working out for you. If you have a LSD, could be that simply the act of emptying all the fluid caused the friction plates to be dry and bind a little until the fluid worked its way back into them. Also, if additive was not used, this will cause binding as well.

There is also a protective layer of material coating aftermarket ring and pinions from the factory. This layer wears away during proper break-in procedure. It has been known to cause a slight harshness of ride and a little whining noise. This material also becomes corrosive over time and with heating and for this reason (as well as others) it is imperative that you not only inspect your gears for tooth wear and proper seating, but change the break in fluid at about 500 miles.

Still, if I had to put money on it, because of the "hopping", I'm betting on the dry friction plates of a posi. Of course if you don't have a LSD, I'd prolly be wrong...

Yes it does have limited slip.....upon opening the cover..there was a small amount of that coating that was worn off....but the gears are breaking in even. I had the fluid changed and will do so again in the near future. Gonna Get My 38"s next week and try her in the woods...can't wait. Thanks for everyones help! I love this Site