I have seen a very strange Holley 4-bbl carb. It is a dual feed...almost like a 4150, yet it looks like a big cube sitting on top of the engine...I have only seen this paticular carb twice, once on a 1966 Fastback (289) and again on my great-uncle's 66' F-100. I have no clue to what this carb is and am very interested in it. Any help would be appreciated...thanks...peace! :-)

i will get a pic as soon as possible

also, i have seen a 3-barrel Holley 4150 Double-pumper...what is up with that?!?!