How much HP can a stock TH400 case withstand in a 3000 lb tube chassis car?
This is with all of the high HP internals.

A lot of people have gone into the 3's with a stock case, and still do. The aftermarket case doesnt seem to be AS MUCH of a neeed because the 400 doesnt need more than 180-200 psi for big horsepower

I can't answer exactly but back in the 90's a friend that owned a transmission shop used to do the trans for a local monster truck. He did pretty well with the truck (Outlaw). Stock case and always said that it looked good internally when serviced. If anything, I think it broke something past the trans in the driveline.

I'd talk to Rossler.
I think 1320 has one for sale.

I think the weakest link is the bell housing so I always use an ultra bell.

we rate our stock case level 5 400s at 2000hp.