SE sleeper

[bonneville55]

I am soon going to be swapping the 3.1 in my 2001 GP for a 3.8 Series II. I 'm starting from scratch on the project and it seems pretty "simple". As far as I can tell so far I can use the transmission from the 3.1. I know I'll have to get an ECM and engine wiring harness for the 3.8. Is that really all there is to it? Just wondering if I'm missing anything important. Do I need the 3.8 mounts and will they bolt on where the 3.1 mounts are?

 

[gtpeddie]

it will prob only be a sleeper with the series II s/c engine they make se's with the 3800 and with a s/c 3.8 you will prob blow up that trans fairly easy im guessing

 

[RooK]

Been there, done that with a 2000 model SE. While I was at it, I threw in an XP cam, headers, and other goodies. I did it with a whole GTP dropout from Ed Morad, replacing the engine and tranny together.

Yes, it's pretty simple, you need the L67 harness/ecm. If your throttle cable has a ball on the throttle body end, you'll have to swap it for one with a T from a 3800. I had to do that as well. I can't remember the year cutoffs for the throttle cable. Engine mounts are identical. The 3100 from 2000+ used the same 4T65E as the 3800s, so you'll be fine, just lacking the HD diff. You'll need the ECM reprogrammed for the final drive in the non-HD tranny though, it's not got the 2.93 gears like the GTP has. If you have any questions, just ask and maybe I'll remember. It's been about 5+ years since I did this, and it's still running lol. Mind isn't as fresh as it used to be on all the details though.

 

[gtpeddie]

nice work!

 

[blueguy]

The '01 SE has the same transmission as the GTP...just different gearing and a non-beffy differential.

It'll be fine if you don't drive like an asshat.