I thought in 97 GM switched them all to 4t65e

 

I emailed Will at Overkill to see if he could reprogram my computer to run a transmission from a 3.8. He said he could, but he also suggested getting a transmission from an Impala with a 3.9. He said the gear ratio is better for performance. Has anyone done this? If so, is it a direct bolt in, or are there modifications needed? He said pretty much everything from 2003 and up is interchangeable.

 

97 everything but the L67 was the 4T60E. 98 Everything was the 4T65E. The transmission from the 3.9L will be the same tranny. All those GM FWD V6s have the same bellhousing bolt pattern which eliminates that potential issue.

The N/A transmissions usually have a lower (numerically higher) gear ratio than the L67 transmissions.

 

Found a pretty good price on a transmission from an 06 Impala with the 3.9 with only 9,000 miles on it. Thinking pretty hard about going that route. The only other concern I have is the electrical connectors. Anyone know if they are the same on all the 4T54E transmissions?

 

I've never heard of a 4T54E tranny, but you shouldn't have to mess with the wiring or anything as long as you get a 4T65E tranny from a 3400 or 3800 Monte/Impala/Grand Prix. You should be able to find them pretty easily for about $200-500 used.

 

Oops. I meant the 4T65E. Sorry.

 

Get one with the hd diff and just swap it in from a gtp

 

The only thing though is that the 4T65E-HD has a different gear ratio and the PCM would need to be tuned in order to accomidate that. You could get a 4T65E and then do an HD diff swap, but that's a lot of work for no real gain except for a little more durability.