[rickpilgrim]

On my 1977 C50 366 is a tall block engine, uses a wider intake manifold with 2 thermostats, has exhaust manifolds that cannot be used with clamshell motor mounts,will not have vac adv on distributor. Has an extended snout on the balancer with 6 bolt holes for the pulley set. Holley carb with either vacumn or electronic connection to the distributor and accessory brackets that are lower (PS) and higher (alt/ac) than you can use on a 1 ton or smaller truck. Also the oil pan would be much larger capacity than the 454.
366 should all have forged crank, good rods and 4 ring pistons. In as much as a 366 looks like a 454, the intake manifolds won't interchange without spacers so you always have 2 thermostats and the way they fit in the 10/20/30 series trucks I can tell if it's a tall block or passenger use engine and many others can also. The 427 TB I'm putting in our 93 K3500 dually is alot closer from valve cover to hydro boost brakes and AC condensor than the 454 would be, and in total height from oil pan to top of carb is very close to a 500 Cad with the Performer intake.