recent GM 6-speed auto, in a 2000 Bonnevile 3.8L?
 

In NC ... Soon picking up a 2000 Bonney SLE .. Lucky enough to find one, in ok shape ... 120,000 miles. Car shifts alright, but that's at the moment (this is an early 2000s GM transmission - lets be real) ... First thing I'm gonna do is have a new trans put in ... Wondering is it possible to put in a 6-speed, from say a 2014-16 Impala, or something ? Can you calibrate it? ... Or does my shop have to hunt down a remanned 4-speed ...
Thanks - Duncan

Welcome to the forum. Is there anything really wrong with your current transmission?
Both the 4t65E and 4t65E HD transmissions are specifically computer controlled, & they will wire & mount correctly for the vehicle. That would be your best bet for a rebuilt, or a GM crated rebuilt.
Calling the dealer with your Vin #, they should be able to provide the correct transmission requirement, final gear ratio and converter stall speed information for your vehicle, which is important to know as well.

Ok, thanks ... Answering your first question - I had a Bonneville, before .. Trans went, right at 115,000 ... so this is a preemptive move. I know right around now (on the odometer) is when they go. To clarify I was thinking a 6-speed automatic from an Impala Limited (last GM W-body, and front wheel drive - like the Bonneville) ... But sounds like there might be trouble anyway meshing it with the pcm. Oh, well. ... I don't think the 3.8L was ever mated to the 6-speed -- And I bet this car {or any} would move along really well, with one! Sounds like a real long shot, though.

Drive your car until it has a problem.

Ummm . . . it's your money, but 120,000 miles isn't a magic number for "when they go". If it shifts okay you may see a hundred thousand more miles from it. Maybe do a filter swap to improve your odds. My original-factory-never-been-out 1997 4T60E is at ~235,000 miles right now and still going strong after I worked out a couple of quirks. I don't beat it, but it gets a thorough workout every day.

1997 is a transition year and known for a few issues. By 2000 they had them pretty well worked out.

What year was your old Bonneville?

Correct, they never put a 6T7x on a 3800, and I've seen no aftermarket controller that would allow this. I agree it would be a good match to get the 3800 Series 2 into its higher-than-Series-1 power band, but nobody's done it that I'm aware of.

NOT a "waste of money" - Early 000's GM transmissions are crap .. Have had more than a few friends, with Pontiacs ... Buicks, and Chevys ... and Cadillacs. ... The trans is going to go. At this mileage ~ sheer luck, it hasn't. Anyway I'm talking to someone now about what it would take to put a 6-speed in it. Sounds like painful, but not impossible.
If ends up a no-go, my shop already said they have a couple partners, that can get a 'new' 4-speed trans. ... In the motor I'm getting the upper plenum replaced (but me and the seller are splitting the $, with that) ... Before that plastic plenum warps, sending coolant where it shouldn't go.
I'm lucky to have found this vehicle.

Please be sure to come back and let us know how this comes out. I'm really curious!

It's been done before. Not here on this forum, but if you Google 'getrag bonneville' you will find some sources. You will need custom trans brackets, custom flywheel, re-programming, body work done, etc. IMO, not really worth the effort. And I think I heard someone once say, the half-shafts aren't strong enough to launch a 3500lb Bonneville.

I think this would be way more possible than the 6T7x swap that Duncan@21 wants to do. I'm really curious how it comes out.