When I had a 400 in a 62 pick up I usually had a devil of a time getting parts. Probably the worst was a new fuel pump, the counter idiot kept trying to sell me one for a 71 Caprice station wagon, what the engine came from, as I was dumb enough to tell him that. I ended up with one for a 57 Bel-Air. I now take a print out with me so there is no confusion and even then I still get an argument once in awhile.