Transmission ID

C9Z- prefix in the engineering number cast into the side of the center case indicates use with Mustang starting in 1969, so it's pretty safe to assume it is an FMX. All cast-iron automatics from late '56-forward are fluid-cooled, meaning there should be an inlet and outlet fitting in the case for the coolant lines that go to the radiator.

Spline count should be for the input shaft, but someone will need to correct me if I'm wrong as I am away from home for several days and don't have access to reference material. Important thing here is to match torque converter to the input shaft and the driveshaft yoke to the output shaft.

Thank you Alan,

I will try to count the shafts tomorrow, when I am back at the car, I was told that it might be a 31 spline as to the original was a 28 spline, not sure what the differnce of the spline count means.
this box came with a different converter/flywheel housing(aluminum? chrome covered) but I also have the original housing(cast iron?)
The aluminum housing is loosing the chrome, can imagine that chrome does not hold very good on aluminum anyway.

let you know the count tomorrow.

regards
ronald

yep, on the converter side the outer shaft is 31 cams, on the output shaft its about 32 if my count is correct.

where would the outlet line and inlet line be? which one is which?
I have to put new cooling lines (or better maybe hydraulic hoses) to the radiator. I do not have the original radiator but a newer for LTD radiator with the tank on the side, between the tank cap and the bottom hose connection on the radiator there are 2 connections, in ads for radiators stated as for transmission cooling or power-steering fluid cooling. which of those connections on the radiator should be the inlet and outlet for the transmission cooling?


regards
Ron