I just found this bit of info:
http://media.gm.com/us/powertrain/en...65_M15_MN7.doc
"OVERVIEW
The Hydra-Matic 4T65 (M15/MN7) was introduced in 1997, and has applications from mid-sized to large front-drive sedans and minivans, using V-6 and V-8 engines. It is a two-axis automatic four-speed transaxle with electronic controls, and features a unique dual chain and sprocket configuration that runs quieter than a single chain design. A stronger version of the chain, with heat-treated pins, is used with V-8 applications."
Anyone with a GXP break a chain?
Cheap upgrade for the 3800 4T65E?
