Quote Originally Posted by Trannyman95 View Post
The best way to replace what you have now is with a trans with the same ID code on it. The SC and non-SC transmissions do have a few changes and are not a direct swap. The SC transmissions, aside the CompG version which I dont know was available in 06, have a different gear ratio that will cause problems if exchanges with a non-SC trans. The SC transmissions have a 2.93 ratio, Tapshift CompG has a 3.29 ratio, and the GXP transmissions have a 2.93 ratio though the bellhousing is different and wont work out anyways. Internally they are the same except for the drive/driven chain sprocket ratio. The SC/HD transmissions use a larger differential that uses a specific matching passanger side axle that wont fit in a non-SC transmission. If the transmission is being rebuilt it is easy to mix and match parts, but to swap one out for another is going to come with a few problems. The gear ratio is something that can be tuned to change also if need be.
Trannyman, isn't there some kind of transaxle casting number "stamped" on the bell housing, that is "supposed" to correspond to either a 4T65E M15 (non-HD) or a 4T65E MN7 (HD) transaxle? Please correct me, either way because, I just cannot remember what they both are. I thought I read it here at grandprixforum.net?

Seems like M15 (non-HD) is a big "923", but is this reversed?

OR could you remind me what both are again, please?

Thanks for reading.

Robert.McArdle@Comcast.net