There were two input shafts used, 17 spline in early FOMs, and 29 spline in later FOM, COM, and FMX.  Even the early HD FOMs, such as Merc, Bird, Wagon, had 29 spline.

John - "The Hoosier Hurricane"

john i believe if you use a merc converter you dont need to change the imput shaft.do you know if the cruise o matic has the same shaft as the fmx.

A freind of mine has a home built C4 behind a 427 inch Windsor that made just under 600 Hp on an honest dyno. With a little nitrous he runs 9.3's@138 in a Ranger PU. No troubles with a C4.

Bud:

As has been discussed here before, the FMX is almost a bolt-in.  It fits the Y bellhousing by redrilling two holes in the FMX case.  With a FOM front pump and input shaft, the FOM converter can be used.  With FOM tailshaft and housing, the original driveshaft, rear mount and speedo cable fits.  And yes, I run one in the race car that has produced 485 rear wheel HP.  No catastrophic failures.

John - "The Hoosier Hurricane"

What I can tell you, is that a C-4 can handle that kind of power. My friend Andrey Jasper Yakolev has a '79 Galaxie LTD with a 450 Hp 302 windsor, and the C-4 is doing a great job.

The '69 to '75 Galaxies made here, came with a optional auto trans, that was a C-4 adapted to a 292 Y-Block trough a FoMoCo bellhousing, developed in Brasil. Those are easy to find, but expensive to ship, due to the weight. As a curiosity, the cars had up to 1973 a Ford-O-Matic emblem on the front fender, even the tranny being a C-4, with full 3 speed.

Túlio Lazzaroni "FORD", Florianópolis SC Brasil.

'74 Ford Galaxie 500 292 V8

'82 Ford Galaxie Landau 302 V8

'98 Chevrolet S10 4.3 V6

'01 Ford Focus 1.8 Zetec

Have a few questions about the strength and reliability of the C-4. If properly assembled with a shift kit and good parts will it handle a 350 horse 312 or overbored 292?

Also, does the Fmx have a removable bellhousing like the C-4? is it adaptable to the back of a Y and if so is it able to be beefed up? Seems like The Hoosier Hurricane maybe runs one of these.

I,m still dreamin,of getting a Y built with all the new stuff inside AND out and I may not wait to win the lottery either.

Bud in Northern Arizona on route 66 in Winslow (standin' on the corner)

If you're American, buy American

631/2 Galaxie 500XL 406   55 T-Bird