I've searched quite a bit and can't find an answer I'm looking for. I bought a 4L80E a month or so ago, research told me it's from an '01 GMC 2500 van, and I'm about to rebuild it. I'm about to buy the rebuild kit I need (won't list site since I'm not sure if they're a sponsor), but they have two separate kits, one says '97- early '01, and the other is for later '01 and up. My question is, how do I tell if my trans is early '01 or late '01?

 

It really won't matter except for the OD roller clutch. That's where big difference lays. You will have to take the OD section apart and post up a picture and I can tell you if it's a late or early roller clutch. Everything else will be the same. In fact, I recommend anyone buying a rebuild kit to buy a late model rebuild kit as it has the Hi Energy frictions. Depending on who you're buying it from and what kit you are getting, it would include a 34 element sprag as well for the late models that would be ideal to use on an early.

 

So you need to see OD sprag currently in the trans? The OD sprag was the only difference I could see between the two kits. Early one had .309 OD rollers and the late one was .195 OD IIRC.

 

Yes exactly. The late model OD roller clutch will have blue plastic on it typically, while the rollers for the early are larger and the plastic is all black.