225 /6's created equal?

Crank register diameter changed in 1968. Hardened valve seats in 1972. Electronic ignition in 1973. Lost the drool tubes in 1975 (peanut head). Cast crank (big end of rods were narrowed also) and air injection in 1976 or '77. Hydraulic lifters in 1981. The only vehicle specific differences I am aware of was in the slants used in 1 ton trucks. :shock: The blocks were selected for minimal core shift, they had valve rotators, and the cranks were nitrided.