as long as it doesn't get beat on, a 60E will last behind a L67 as long as a 65E-HD...

but who are we kidding here? it's gonna get beat on.

and yes, all L67 cars in 96 got the 60E HD. i'm not sure what all was special about them, but they were 96 only.

Isn't the chain in the in the 4T65E stronger than the one in the 4T60E?

presumably, the dual chain setup in the 65E is stronger.... but that's compared to a regular 60E chain. the 60E HD MAY have a beefier chain... someone who's actually taken apart both HD and non HD would be a good resource here.

I'm positive I didn't quantify it on purpose :) I'm not as familiar with the 60's as the 65's. But in the 65's the trans is a trans is a trans and only a couple interchangable parts make it an HD. Pretty sure the 60 is the same way, except GM changed pitch of pinion, tooth count etc etc, nearly every year. That makes them seem much less interchangeable. But if you know the trans, you can do it easily.

As for chain stretch and the 60 not being able to back up the S2 L67, the issues the 60 has is less vanes in the pump. Therefore at high rpm where the S2 shines the trans cavitates and can't pump enough fluid. The chains are frequently modified to be used in 65's as a single chain solution. Recently with the 5.3L being backed up with a 65, the HV-093 V8 chains were developed. They are supposed to be stronger than the 65's original chains.

There are many faults with both transmissions. I wouldn't necessarily say that either is not suggested. I'd suggest doing the research and learning the various pro's and con's to both, then making an informed decision.

Big things
60's
Like to eat diffs
Run hot
Vacuum shift modulated
Don't like rpm

65's
Eat 4th clutch hubs
EPC soleniod issues
Fully electronic and programmable


Add power and you can abuse anything into submission. Just ask the various race transmissions that have been behind my engine (aka "Shredda")