As i think I understand it, the Bonneville'* got the 3800 II */C before the 4t65-e came out, so the got the 4t60-e HD version tranny. Does anybody know what the option code was for this HD version of the 4t60-e.

From what I've read, the 4T65E and 4T65E-HD found behind todays L36 and L67 Series II Engines wasnt introduced until late 1997, and fully replaced the 4T60E behind L36 and L67 cars from 98 up. In other words, I think all models prior to 1997 had the 4T60E, both Supercharged and Natrually Aspirated. In 98 however, all L36 3800 series II non-supercharged engines were mated to the 4T65E, and all L67 3800 series II Supercharged engines were mated to the heavy duty 4T65E-HD. I'm not quite sure if this answers your question as far as the actual code (like in the VIN?). That I am not sure about but a simple call to a good, smart dealer'* service department may be able to answer it.

Hope this helps somewhat.

I have heard the exact same thing. I had also found a site once where you can enter the parts code from the the bottom side of the trunk lid and it woud tell you exactly what it has per the build request. I tried it a while ago and it only defines it as the four speed automatic and nothing more. Your best bet is to go to the dealer or a transmission shop. Either place should be able to tell based make, model, etc...

Basically in 1997 all Bonneville'* got the 4T65E and in 1998 all Grand Prix got the 4T65E. That'* all there is to it.

And in 2000, I believe all bonnevilles got the 4T65E-HD???

or at least the SSEi did.


Lee

Let me clarify. All N/A cars whether Grand Prix or Bonneville get the 4T65E. All supercharged 3.8'* ie GTP'* and SSEi'* get the 4T65E-HD.

Krusher is exactly right, even in 2002 this still holds true.

I wonder what physical differences there are between the 4t65e and the 4t65e-hd...


what makes it "heavy duty"???


Lee

The differential pin diameter is larger for one. I think that it is mainly just larger internals, and the HD version got the larger torque converter. And it got a higher final gear, 2.89 compared to the 3.29.

What I was actually looking for is the RPO number (trunk lid number) for the 4T60-E HD, mainly to figure out which one that I have, the POS normal one, or the POS HD one . I have a 94 Grand Prix GTP with the 3.4 DOHC engine, and it just tears up transmissions. If in fact I have the normal 4T60-E, then when my transmission blows I will drop a HD one in. The only problem is that I have no idea which one I have, its RPO M13, i know that.

Thanks all
Brian

I found this roll of paper in my trunk that has a tone of codes on it from the assembly line. Actually two rolled together. Both have a huge list of codes and options. It also has my cars vin on the sheet. On my sheet the m13 says exactly this

MX0 AUTO TRANSAXLE
M13 4SPD TRANSAXLE

hmmm I wonder what that means. lol

You might find the same paper in your trunk lid.
ty