I have 799 heads on my L33. I was just reading a long thread on the Corvette forum where there was debate on whether the 799 flowed better than, worse than,, or equal to the 243 castings as quite a few '06+ vette owners have the 799 castings while a majority have 243's.

Now even though the casting is the same I wouldn't have the same size ports on the 5.3 as the LS2's, would I

 

The 799 head was originally a pre production LS6 ZO6 head. It's virtually identical to the 243 casting in every respect. It flows the same as an average 243 head on my bench. I don't know the logic of GM using several different casting numbers for the same part. It's the same way with the L92's. I'm sure they have their reasons.
Besides the difference in intake valve size, the 799 has a much improved intake and exhaust port over the early 5.3l heads.

Richard

 

Weirdness, GM seems to build the majority of one family of heads by one part# and for some reason in much smaller quantities produce the same or near same head with a different part number.

I have are rare set of 6.0L 035 casting heads, aka 317's

 

Interesting. Thanks for the response guys.

 

with the older engines the difference incasting numbers often ment the parts where made in different lacations. I can't give you num. for reference but i ran into this on the late 80's early 90's heads. I had the of the same heads, all three with different part numbers. Turns out one was made in canada, one in Mexico, and one in california. They flowed different but the americn one's were the only ones you could safely port and polish.