That must be a Windsor in that 94, Ford discontinued the M's in the early 80's. And if it ain't broke, don't fix it.

 

Had the 351M in a '79 Bird; what a killer in town on gas mileage (couldn't buy 10 mpg)! Get it on the hwy, no kiddin', 25 mpg at 70 (bought the car in Maine, without air conditioning option.

Read a couple of articles concerning Ford retarding the cam to meet EPA specs; use the cam sprocket from '68 or '69 Cleveland to advance the timing for power, do some engine work and get high teens to low 20s for gas mileage.

Cleveland and Mike, sweet!

 

I was involved in a swap from 3.90 to 4.60 in a 1975, F150. 460 and C6 trans. were out of about a 1979 F-250. 460 engine mounts were purchased from dealer for the 1975, F-150. Swap went perfect except A/C pulley would not line-up.

My brother-inlaw was the engineer on this project. We went to a neighbors salvage yard and looked at many Ford cars from the mid to late seventies. He looked at a T-Bird (about 1976), with a 429 and said, "everything, pulley and idlerwise on the engine will work exactly. Lo and behold, we took all pulleys and idlers and belts off of the 429 and it was a painless swap.

 

i like my 390 in my 76.everybody who has a big block has a 460 and i like to be different.that does make it harder to find parts,but oh well.

 

If you're really thinking about the 351M, look into getting a 400 crank for it. Same 4" bore but with .5 inch more stroke. They used the same 6.5 inch rods. The big gain is that when I built my 400 I wasn't aware that the 400 pistons had the same compression height as the 351 Cleveland pistons. I couldn't find any company that offered pistons for the 400 that were anything above the stock dished pistons. (same goes for the 351M) However, there is an endless variety for the 351C pistons. I shaved the heads on my 400 to try to gain some compression, but if I knew it at the time I could have had flat tops instead. My 400 was .030 over, Edelbrock perfomer cam+intake+roller timing chain, 3 angle valve job with milled heads, 600 CFM carb and I believe the headers were 1 7/8 primaries into a dual exhaust system. Behind that was a C6 with a TCI rebuild kit and B+M valve body shift kit with a TCI 2500 stall converter. With 3.50's in the rear end, my '78 bronco would do a quarter mile in about 15 seconds flat. It wasn't exactly a rocket, but it sure did **** off alot of guys on the local boulevard with their 305 "HO" camaros after watching a big heavy 4x4 drive away from them. LOL It did make alot of bottom end power if that's what you're after.

 

I do believe that the 351M is a 351 block with a 400 crank/modified heads/rods and pistons. Also, the 351M and the regular 400 have different harmonic balancers, I believe the 351M is thicker (don't quote me, it may be the other way around). I pulled a 351M out of a 79 two weeks ago and hauled a 460 to go back in it a week ago. I believe the 460 had it by less than 200 pounds. The 351M is a good engine, definitely durable, not the best, but certainly not the worst. They make decent torque, and everything minus your motor mounts should match up. I'm pretty sure the tranny will, but I think you'll also need a flywheel. The regular 400 and the 460 don't have matching flywheels, so I'm pretty sure the 351M won't match up, either. Good luck, and we need pics of that truck!

 

I had a 79 with a 460, it was in the family since new. I put a 351m in it and drove it for a year or so. It had less power and got no better gas milage. I rebuilt the 460 and put it back in, in my opinion it is a much better truck engine.
Four years ago when I sold it, it needed paint and a windshild, the rest was perfect. I advertized it in the paper for 1500 and had people fighting in my front yard to buy it.