I found that way interesting too. stock drum better have a rev limiter at below 6000.
aftermarket (steel not cast) 8000 rpm max.
All alu. 8800 rpm max.
These are all to distortion not fail, because if i'm going to spend big dollars on a part like this...........i want some fudge factor figured in.
my next rebuild will have one of these.....just can't decide on the all alu. or the steel.......
I do not recall who makes it, but there is an aluminum 727 drum on the market that has a steel sleeve on the outside so you do not get all the aluminum in the trans fluid and the associated maintenance.
I just wish someone would make one for the 904. But Tcs tells me it may be coming.