They are near the same. The early models had 7/16 holes in the crank for the flywheel same as the smaller 6,s & v-8,s. The latter ones had 1/2 in. bolts. You can drill the small hole flywheel out to use the bigger bolts. The early ones had the temp sender in the therm. housing & latter ones had an opining in the head. 73 up went to small belt pulleys & damper. 1 ton & smaller had 2 in. exhaust pipe outlet like the smaller engines & 1 1/2 ton up had 2 1/2 in. outlet.
