I've got a C4/302 combo in my truck presently, am looking at buying a 351M locally out of a 77 pickup.. Will the 351M mate up to my existing C4?
If yes, will it mate up to a C6 if I decide to get one in the future?

If this works out I'll be bugging ya'll later about "cranking" it to a 400.

 

351m/400 is the same bellhousing pattern as a 460, so a C6 is the likely one.

 

No. 351M/400 only came with a C6 if an auto was selected.

Even if you managed to, the C4 will explode like C-4 under the torque of the 351M/400. C4s were made for light V8 engines (221-351W).

 

there are factory(and aftermarket) bellhousings to do it but they are far and few between, the racers grab them up to run stroked 460's and C4's. i wouldn't worry a minute about the (lack of) torque output from a stock 77 351M or 400 for that matter.

 

Ford used C-4's in the mid to late 70's behind 351M's in some of the larger cars like T-birds but they were pan fill C-4's.If you have a case fill C-4 you are out of luck unless you buy an aftermarket bell.You see them on ebay all the time listed as 460 C-4 bellhousings.I have one out in the garage for a future 460 Mustang project that I bought from a guy in the local Auto Trader but I have seen them in the wreckers but they are rare.

 

No F100/350 with a 351M/400 ever had a C4 transmission behind it. Some of the cars with 351M's used C4's, some used C6's, and even a few used FMX's. All the cars with 400's used a C6.

 

The correct summation would be that the vast majority of 400 equipped cars had C6s. There were an unknown number of 1973 and possibly early 1974 Torino/Montego/Rancheros that did come with the 400 AND FMX tranny. These are the ones with the small bellhousing bolt pattern. Granted these are as rare as hens teeth but Ford did make them.

 

C4 was available in Fseries for 1 model year only, i forget which year and what engines.

also, there is an FMX trans bellhousing with the large 385 series bolt pattern, i'd really be surprised that not a single 400/FMX combo was produced?

 

C4's were available in F Series trucks from 1965 thru 1977, skipped 1978/79, and were back in 1980/81. While the vast majority of the engines that used C4's were 240/300's and 302's, in 1965-67, some 352's came with them also.


The cars with 400 engines used mostly C6's but some full sized Fords and Torinos used FMX's from 1973 thru 1976 (as was pointed out above, and that I erred on). A few 1973/74 big Fords with 400's used the oddball BW-12 transmission (PHE-A; A1), for commercial (taxi) application only.

 

it might be a certain engine/C4 combo that was a 1 M Y deal?