well going by the bell housing code C4 AP 7976 - A it seems that C4 is 1964 AP is generic/ galaxie auto trans 7976 i have yet to find as well as A....this is what i can figure at best maybe im wrong.
Ronstang, just thinking back to when I changed over a 66 mustang 200cid into a 64 fairlane w/2spd. Both were 6 cyl but I think I remember having to change over a locating stud on the back of the engine to fit the different bellhousing. Do you recall anything of the sort? Not that this would help here, but it would mean that the 200 fits both bells.
Found this on google: http://66.102.7.104/search?q=cache:...+"5+bolt"+bell+housing&hl=en&client=firefox-a
oddly enough, it's from this site but I can't find it here using the search.... oh well
it mentions the differences of bell housing matings to the tranny itself w/regard to the pump bolts and also mentions a difference in input shaft splines...
IF you have a 5 bolt...
I have no more info.... good luck.
edit: just noticed the client=firefox-a on the end of the link.... you may have to modify this if it does not work for you (running ie or something else)
Ronstang, just thinking back to when I changed over a 66 mustang 200cid into a 64 fairlane w/2spd. Both were 6 cyl but I think I remember having to change over a locating stud on the back of the engine to fit the different bellhousing. Do you recall anything of the sort? Not that this would help here, but it would mean that the 200 fits both bells.
I have no experience with 6 clinders as I have always had 8 cyliinder Mustangs. I do know that the later and larger 6s had the same bolt pattern as the small block V8 and I think the 170 and 200 ci 6 cylinders had a smaller bellhousing.
If you look inside the bellhousing, there are some bolts there that you take out and the bellhousing comes off. Then, locate the proper bellhousing from a junkyard, bolt it on and try again. I ran a six cyl. tranny behind a stock 302 for years with no problems. When you up the power, it will become an issue.