Well, Last Monday I sold a guy the heads of my L98 in the garage. I just checked one casting number and gave it to him and assumed the other was the same, but they weren't. He called to day and told me, so I bought them back. One is a 191 and one is a 193. Whats the difference? I know they're both pretty much useless for any kind of performance.

LO3/LO5 swirlports. Never used on L98.

FWIW, I use this as my gm casting number bible, very helpful. www.mortec.com/castnum.htm

Well I dunno how they got on my motor but is there any difference between them?

I was under the impression that 191's were 58cc. However, Mortec says the 193's were used on 305's and 350's. But, they've been known to be wrong.

FWIW, I had an '87 LB9 with one "proper" head and one swirlport. Apparently it had been rebuilt (it was .040"-over), and one of the heads was bad, so they just stuck on another "305" head, with no attention paid to the different "305" heads out there. Most likely the same thing happened with your L98, but with both heads.