I am pretty sure i bought a truck with a 460. The truck came with a 351M. I know the motor was swapped. I am told that it is a 460 and so far, it all checks out except for the plugs.When I went to chage the spark plugs, the ones I took out were different then what I bought. It seems the right spark plugs are the small ones. My heads take the big fat ones. Can anybody explain this? Are these aftermarket heads.

 

I'm not sure but I have never seen big plugs as you call them in any late models, so my guess is they are like late 60s, maybe early 70s the small plugs came in I think early 70s. Someone correct me if I'm incorrect.

 

The later ones took a Asf 42 or Bsf 42.

The earlier ones used a Bf-42 or what is now the Autolite 45