This isn't f-body, but I just bought a 2001 Blazer 4x4 with 141k, and other than trans cooler, what else should I do to help extend the life of this trans, a shift kit? I have heard that changing the fluid could actually make it worse, is this right?

 

A shift kit will probably shorten the life of your tranny. It puts more stress on it by making the shifts firmer. And you definitely want to change the fluid. An auto tranny uses the tranny fluid to shift.

So basically you want to change the fluid and filter regularly and don't beat on your tranny. It is possible to make an automatic last for a long time, my Dad has over 200k on his stock 4L80E.

 

You do want to change the fluid as stated above and a tranny cooler will help too. That's about it. Don't use any additives that are advertised because they are a waste. Regular fluid changes is about as good as it gets.