I had three different tops at one time, four if you count the last Dominator top. I have one remaining the number is 7164 and is on a Hemi Blower intake, very short under two inches and a slight ram to it.. I also had 1911 two normal holley four barrel spacing.1912 or 1913 is for the Doms. Can not remember the other numbers that I had but it was for Normal Holleys. The dom top is ramped also and might be this way so the first carb does not block the air flow of the second carb. Under the carb the plenums are much bigger in each application do to the height of each top.