what are the diferences between the cast number 374, 643, and 561 heads?

i looked em up on mortec.com and here is what i got...

10128374...92-up...350..........Gen.II LT1, 53cc, angle plug,
aluminum, reverse flow cooling,
175/68cc ports

10207643...94-96...350..........Gen.II LT1, aluminum, reverse
flow cooling, 175/68cc port volumes

12551561...96......350..........Gen.II, "LT1", aluminum

I also looked em up on a couple of other sites (ok like literally 8) and
Got all the same info... nearly word for word...

My question is. Is one better than another? and will all 3 bolt up to my 96 Z the same as each other. (i.e. all my sensors in same location ect.)
I have a set of pacesetter non emissions long tubes on the way that are gonna go on at the same time and i would like to have no issues.

Thanks

 

I replied to this same question on another board with a link to a thread here. Are you sure you searched? There have been [seems like] tons of head discussion threads here.

 

posted same question in both forums in hopes for answears.