The heads came in several styles

The C engine (1/2 ton) with more emission
The J engine (3/4 and 1 ton stuff

There are a bunch of different pre-cup designs.....DO NOT MIX AND MATCH THESE AT ALL.

Run all matching pre-cups.

Best to keep matching heads with matching cups.

The injector angles came into play when the turbo came into the game....Make more room to clear the turbo and such

Short injectors or long injectors.....Fine or coarse thread injectors (Coarse thread...Early 6.2)