Pretty much the same.

904 over-running clutch cam (stock) is riveted into the case, where the 727 is pressed in and held by a socket head set screw.

904 low/rev band linkage is a little different. The 727 uses a bracket that's held on a pin thru the rear of the case. The 904 has a slightly different set-up.

904 front planetary and annulus gear are held together (2.74 1st) with a snap ring, 727s just slide together.

904 front pump has two complete halves, 727 has the main pump housing with the reaction shaft support bolted on the back side. You have to make sure the 904 pump halves are aligned. I use a large worm screw clamp, or you can install the pump backwards into the trans case and tighten (torque) the pump half bolts.

904 uses one large (stock) direct clutch piston return spring, 727 uses a multiple peg piston that uses 6-15 springs.

904 forward clutch housing and splined hub are one piece, 727 forward clutch housing and splined hub and held together with a snap ring.

If you have the Carl Munroe 727 book, you should'nt have any problems with the 904.

John