I have a 1980 F250 with a 351 engine. I do not know how to tell if it is the 351 M or Windsor. I do know it is supposed to be in the VIN but can not find out for sure how to read it since all the resources I find online require a 17 digit VIN and mine is only 11. My VIN is X25GKHD3704 Any help would be appreciated.
Thanks
look at the valve covers. if they have a raised part where the oil fill is, then drop down to a sort of flat cover, it is a 351M. if they are the same size full length, it is a 351W this is a picture of a 351M cover
Also, IIRC, the M will have the thermostat housing bolted to the block while the Windsor has the thermostat in the intake manifold....
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