Where is the casting number or engine ID number located on a 351M from a 77 F100......Thanks

 

It doesn't matter because the engine was designed for a full size Ford car.
The 400 will also have the same casting numbers.

The 3rd digit will be an A and the 4th will be an E .

What is it you are trying to figure out ?

The best info is on a buck tag usually located under a mounting bolt for the coil.

Btw, this is an engine question and would be best posted in the 335 engine series forum.

 

i'm trying to order a new long block assembly and i keep getting asked which engine is it. There seems to be four for that year model

 

Why not just order a 1971 400 instead ?


https://www.ford-trucks.com/article/...00_Engine.html


The only way to tell the difference is to measure the stroke.

 

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What are the advantages of the 400 over the 351 and will i have to make changes or will it slip right in

 

no changes at all. the only difference between the 351M and the 400 is the crank and the pistons, all internal. externally the engines are identical. if you need to have the proper emissions equipment for a visual inspection you should order for the year of the truck, otherwise the 71 400 should have more compression and none of the smog passages in the heads. or you could order a 71 400 short block and put the correct year smog heads on it yourself, it'll be better than a smogger long block. that is IF the rebuilder does use the flat top pistons(instead of dished) for a 71?