Hi guys... I have a 5.3L from a '03 Suburban that I swapped into my '91 Z28 and is running great. Looking to get the transmission mated up now - I found a 4L60E from a '97 Firebird (RPO code M30) and I'm just wondering if this will connect up with no (or minimal) problems to this engine.

Can anyone confirm?

 

97 won't mate up properly. It's going to need an adaptor or the flex plate with the adaptor built in. I think anyways. I assuming the crank flange for the flex plate bolts on the LT1 are the same as a regular SBC. The LS is more recessed thus requiring the the adaptor.

I'm not a 100% sure on this as this is all information I've read online.

[Edit] Recessed isn't what I mean. The flange is flush with the block on the LS

 

I cross-posted over to LS1Tech because I needed an answer quick and you are correct. They wont mate up exactly, but it looks like a flexplate with the adapter flange will make everything work.

I think I'm probably good to go then. I'm going to try to pick this up and hopefully all goes well.