Also ford was clever in marketing the new 351m in 1975 still calling it a cleveland 351,but by 1976 the cat was out of the bag and many who bought a new car thought it was a 351c,which had been canned since 1974,it amazes me even today yanks on you tube so many people have no idea if there engine is a 351m or 351c ,to them its just a 351 .
i want another 400 or 351m just for the hell of it,the 351m deck is not as much down the hole as a 400 at 65 thou odd,very hard to find a 351m here in aus but i have seen a few over the years for sale,they use the same rods as a 400 but a taller piston and 3.5 inch stroke ,the 351m was made from 1975 to 1979 ,and the 400 from 1971 to 1982,that last 400 i rebuilt was very rare being a 1971,i have been looking for the ultra rare 1973 small block bellhousing one,sought of like finding a nazcar pillow block at a garage sale for $100 lol.
Ford did some funny things back in the day, they developed the FMX from the BW and used a Ravigneaux planetary set, but produced that box alongside the C4 and C6 which used a completely different Simpson planetary set. Then, when they were done making the FMX in the late 70s, they developed the AOD from it while the C4 and C6 were phased out. So in a roundabout way, the FMX design predated, then outlived the other gearboxes that were supposed to replace it.