Just a heads up... Sometimes in a 4L60e with that many miles, a shift kit can put a bit of added stress onto some parts that may already be tired. Especially given the more aggressive nature of the HD-2 kit. Not trying to discourage you, just sharing past experience. Ive seen several sunshell failures due to this and also a handful of band failures.

 

Ive been thinking about that, and a buddy threw that out in a discussion lastnight. Maybe Ill just upgrade the cooler and do a fluid/filter change. Then keep up on the fluid till the trans dies.