Truck has 106K 2005 3500 completely stock, last week I had a small trailer hooked (2500#) and the trans slipped and then shuttered a couple times on light acceleration and cruising. Pulled off and the truck has been parked. Checked fluid looks to be full warm, in neutral on a level surface and doesn't smell burnt. Perhaps a little low, it's hard to read, does seem thin, no idea if PO had it serviced, I see it's due at 120k. I'm going back for the truck tomorrow.

Is there any chance the trans isn't in need of a full rebuild?
When I take it in are there tests I should ask for that may pinpoint something on this trans?
Anything I can try that may be a DIY fix or something I can have a shop try that they may not do before recommending a full rebuild?

 

Well, are you sure that it wasn't just the TC locking and unlocking?

I'd start with a fluid change with filter, look what you find in the pan. Also check the bands. Use the correct fluid!

 

Didn't seem like the TC, revved without acceleration twice, then a good hard shutter.

I'm seeing the +4 as the correct fluid. Can I adjust the bands on a 48RE? For the fluid change, just what comes out with the pan or is there a way to do a complete changeout?

 

Yep, +4 is correct.

A complete changeout is almost impossible without pulling the trans and disassembling it, including cutting up the TC.

But you get a lot if you remove the pan, remove the filter (save it in a clean place for further diag), loosening the VB bolts and letting it drip.

The bands are adjustable in he 48 RE, I strongly suggest you get the factory service manual for your year, less than 50$ from eg Geno's Garage, and you have the correct torque values etc.

If the trans improves a lot after the fluid change, repeat it after a short distance (more than 10 miles, less than 1000- just dilute the "bad fluid" quickly.

Inspect the contents of the pan and also inspect (maybe you need to cut open) the filter.
Anything looking like part of a shaft seal or o-ring is bad news.
Sludge in the pan is inconclusive- it was clutch material, but we do not know how much of it has already been cleaned away at previous oil changes. (So we don't know how much is missing)

If you are handy with tools and have time and patience you can rebuild these transmissions yourself. You will need the factory service manual, and you may consider stuff like a shift kit, and some uprated clutches.

 

Thank for taking the time and giving me this detailed reply, very helpful. I'm handy, but this would be waaaaay beyond my capacity at this time. Would love to tackle something like this some day though. The plan is to pick up the truck in the AM and take it to the trans shop for them to diagnose. I'd like them to do the filter and fluid and check the bands. I usually do all this stuff myself, but had a nerf football sized tumor pulled from my pelvis this summer and can't quite do what I used to!