Are "Fordomatic" and "FMX" transmissions interchangeable?

G

Gatopescado

New member
Hi Everybody!

I've got a '65 F-250 with what I think is the original Fordomatic, or "Green Dot" transmission. The rear band broke, so I don't have reverse. I yanked it out and took it to my transmission guy, and he is skeptical if he can get a band (we did find one that was relined around 1970! :eek: ) that would be reliable, and he didn't seem too enthusiastic about overhauling this beast anyway. He is proposing a C6 swap. He just happens to have one to rebuild that will be a bolt-in upgrade. Lots of money, however.

A guy down the road has a FMX just sittin' there. Darn little money. Of course, he's not too sure of its history. But its cheap enough to maybe take a gamble. (Edit: FMX is a 1970)

Can I bolt the FMX up to my big block bell housing and bolt on my truck tail-piece with the bolt-yolk and call it good? The mounting holes look right. The dipstick, linkage and lines are all in the right places. The cases look the same. What am I missing? What do I need to know?

Sorry if it sounds like I don't know what I'm talking about. There is a real good reason for that. ;)

Thanks for any help knowledgeable Ford people can give me.
 
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390. The C6 the guy wants to rebuild has the correct bellhousing. The FMX "appears" to have the same bolt pattern to bolt onto my existing bellhousing. I guess what I'm not sure of is the input shaft and compatability of my existinig tail with the truck yolk.
 
You will need to drill the top two bolt holes in the FMX case to match the holes in your bellhousing. There is sufficient meat in the FMX ears to do this. Use your COM front pump to match your converter drive. The COM tail shaft and tail housing will bolt to the FMX. Make sure you still have the correct end play in the rotating assembly. Watch the tail housing gasket, the FMX gasket may not quite cover the COM tail housing flange at the bottom corner, causing a leak.

If you want a good used rear band, I have several available. Your trans guy may be reluctant to work on your 50+ year old transmission because of possible later problems which he would have to cover under his warranty. Maybe he would do it if an agreement is reached before the work is done.

John
 
Up-date:

Much thanks to John and this community! Got the Cruise-O-Matic repaired and I stuck it in the other day, and all is good.

3 speeds one way, and one the other way!
 
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