Found a 1999 4L80E with 75k on it out of an 1999 Chevrolet 2500 for $400 obo. It is completely stock. I haven't gone to look at the trans yet but, I am going on monday morning. I know I should look to see if the trans has the location for the top mounting bolt and see where the cooling lines run. Any other things I should look for? It's going in a 2006 GMC Sierra 5.3. I know the 99' won't have all of the updates internal wise but, are they just as strong as say an 05' or just as capable when they are built properly? When it gets rebuilt will I be able to update all the internals to make it like the new models? I've heard that some of the internal updates can be done to the older trans, but some updates cannot. Thanks guys

 

I personally like the earlier LS1 units just like the 99 you have there. I feel that the early OD large roller one way clutch is stronger and also the later units seem to have more issues with bushings wearing prematurely. I know I have seen more issues with the 04 and later units. Some builders will argue this but its what I have seen. I know some builders prefer to stay with the earlier units that are not of the center lube design. Guess it comes down to what you have to work with and go from there.

 

The 1999 model year 4L80-E was the first year with the wider gears in the two rear planetary gear sets. Also the first year for wider second gear band, used only in manual second to prevent overrun.

Most the updates to the 4L80-E over the years have been favorable in terms of durability except for one. Most builders would agree that the redesigned Overdrive roller clutch that was introduced in mid-2001 does not have the same torque-holding capacity that the previous design did with the larger rollers.

If you have a 1999 unit it will have the lube return port in the back ('97-up), the larger gears than previous years, and the favorable roller clutch. I think it's even got the top center bolt hole on the bell, that was either '99 or 2000. Even if it does not have that hole it'll still work.

 

^^Mostly true, except the later style lube design usually has more lube failures, killing the planetaries.

 

So is 1999 the year to have? If not, what's the "best" year?

 

Thanks James & Vince for the knowledge!

I found another 4L80E from a '99 except it has over 200k on the trans. Is it still a usable trans with that many miles? Still a good buy guys? Any concerns with the high milage except for an obvious rebuild?

 

Ttt...

 

Basically with a good builder, the year doesn't matter.

 

I would pay close attention to the valve body for worn bores. Sonnax makes a few different products to address these issues. As far as the rest of the trans the hard parts are either good or will need to be replaced. Its kind of a procedure thing that builders should do when building any unit.

 

I was going to go ahead and get this trans but, I called a few trans builders in Northern VA and all of them wanted $1800-$2800 to rebuild the trans to factory specs. If it is going to cost that much then why not just buy a built FLT trans? I'm trying to keep my swap under $1200 if I can but, I can see my wallet burning already. I'd like to find a trans with decent miles so it doesn't have to be rebuilt.

Thanks again guys.