904 is about 35 lbs lighter then a 727 which is mostly internal. A 904 is at most about 2 tenths faster then a 727 with converter being equal..

I picked up .15 and about 2 mph back in 1993 went i changed...and never looked back.

all 3 cars in signature below are 904s,,,they are so easy to build that even I can do it...

there was a magazine article many years ago that listed the hp required for each trans...

powerglide was about 18

904 was 24 ...same as ford c4

727 was 45 hp...about the same for T400

and the Ford C6 was the worst...

maybe some has the chart saved somewhere