Contrary to popular belief, you'll find that most your truck engines, espically the '68-72 and some '73s came mostly with the 360, be it the standard engine. Just about all of the '67's were 352's and a few were 390's. I think the 390 made the options list in '68 but was seen more widespread from '69 up especailly in the 3/4T and 1T trucks. tha only way to know FOR SURE which one you have is to ID the crank itself.