I will crawl under there sometime today and see if I can find a tag or at least take some pics. With the cam it has in it, it should really have a stall converter, but do they make one for the FX/MX? I don't want to overdo this because it really is just a street cruiser and have no plans on racing it. I have another car for that purpose. Again, this into is very helpful.
The FX and MX look so close to one another it's hard to tell the difference from the case but the pan is slightly different. Here's a link to look at if you cannot find a tag or it's missing.
Ford Transmission IdentificationPan gaskets and filters for C
As for the converter regarding stall. That's the main problem with these older Borg Warner designed transmissions (FX, MX and FMX) is that aftermarket parts and upgrades are slim to non-existent, unlike the C4 and C6. I rebuilt an FMX for a friend and he had a heck of time getting just rebuild parts. He had to send his bands in to get relined sort of thing because no one is making the bands from scratch.
Your best bet, if you have an MX and decide to stick with it, is to call around to some aftermarket trans places and see if you can send them your old converter and they can slice it apart, clean it, alter it for the stall you want, then they can re-weld it and balance it for you.
Even torque converters for the C6 mating to FE's apparently are getting scarce as the place I bought two rebuilt stall converters with Torrington upgrades required a core charge on the old converters, so I had to send them my two old ones, which is something you usually do not have to do for other transmissions.
As for rebuilding the FMX, after rebuilding a couple 700R4's, building up a 4L60E, a TH-400 and 2 C6's I was less than impressed with the construction and size (torque capacity) of the parts of the FMX. That's just my opinion though.
Good luck and keep us posted.