I have an auto and would like to keep it that way. Are there any options as far as upgrading an auto or can they handle 350-400 hp?

You need a good external cooler for one. Dean Marcum was going to come up with a list of small mods for it. I dont know how that list is going.

Back to the cooler. It is one of the best mods to do to any automatic transmission.

ok, thanks for the tip. I will have to get my hands on one.

with a good cooler and a resent rebuild how much power should it be able to handle

I'd say about 400hp. There are (were at one time) some "streetrod" shift kits for it. They improve the oil flow to the clutch packs, so you have quicker shifts and more pressure, so less chance of clutch pack slipping.

If there aren't any kits anymore, someone out there may know/remember how to drill out that valve body plate to accomplish the same thing.

I've drilled several Fords and Chevys with good results. I learned how from the auto teacher at the college.

You'll also want to upgrade the torque converter, and the drive shaft and u-joints if you go above 400hp. Go single driveline, not split.

try out levelten.com they have some auto tranny upgrades if im not mistaken. I know for sure they have supra tranny mods so check them out.

Screw stock want auto trannys. If you want to stay auto and you mind spending the money, I suggest powerglide! It expensive like $4000 but its the last tranny mod that you will have do. Virtual Works, Dana is working on an adapter so we can put it on our 7Ms.