I just picked up a 91 isuzu trooper with a TBI gm 2.8 in it. Had a blown head gasket when I got it, pulled the head off and both are screwed. The GM casting # is 14054884 on both heads. I have found a good deal on a rebuilt set of heads, casting #14054882. Can anyone tell me the difference?

Check the size of the valves. Your earlier numbered heads may be off a carbed 2.8 and may have smaller valves.