Transmission or Rearend Problem?

[Sixball]

I put a 454 and TH400 in my 94 Shortbed Standard Cab Chevy 1/2 Ton. Total computer delete. I also installed a Power Trax “lunchbox locker”. No issues for about 200 miles. Tuning the 454 and doing a few burnouts with no issues until last week. 3rd Gear take off from a dead stop, laid rubber for about 30 feet then the engine just revved while still moving forward. I let off the gas thinking I broke something but Truck continued moving forward. With my foot still off the gas, I hear the back tires catch like power was going to them, I slightly press the gas and it drove fine for the remainder of the trip ( 10 miles).

I checked the U Joint, no slop, tight bolts etc.. I drove another day about 25 miles, no hard acceleration. No issues until almost home and I felt a clunk - with the rear tires catching traction again while just driving normal at 30 MPH.

Where do I need to start looking? Rear end or Transmission?

[kwmech]

Definitely the rear axle. Those 10 bolts weren't very strong to begin with. Pull the cover and have a drain pan ready to catch the debris. Probably chipped a few teeth off the pinion and/or the ring gear

[Sixball]

Thanks. That’s what I suspected (rearend). What’s a suitable swap for the rearend? POSI in the Pumpkin? Or total axle swap?

[kwmech]

I'd recommend a 14 bolt semi-float that GM put in the trucks from 88-98? truck was the SS model that had a 454. Going to a little hard locating one that is 5 lug, but they're out there

[Sixball]

Originally Posted by kwmech

I'd recommend a 14 bolt semi-float that GM put in the trucks from 88-98? truck was the SS model that had a 454. Going to a little hard locating one that is 5 lug, but they're out there

Yeah, 6 Lugs are readily available, but I don’t want to switch wheels and brakes. The search is on.

[kwmech]

Originally Posted by Sixball

Yeah, 6 Lugs are readily available, but I don’t want to switch wheels and brakes. The search is on.

Maybe check on whether or not the 5 lug shafts will swap out for the 6, then either get the 5 lug drum or re-drill out the 6s.

[geezer#99]

Your description is more like trans problem.
Drop the pan and see what’s in it.