I have an old stall chart, the slant TC was rated 1800-2100, vs 1700-2000 for the 318. If You stop & think about it, w/more torque the 318 would stall the same juice-
wheel higher not lower, so there's no doubt something was different OE. I doubt the /6 904 converter is somehow inferior in build strength to an 8cyl. unit, what would
they "cheap out" on & why?