Here is our blower top plate to fit a pair of two barrel carburetors atop a GM 4-71 supercharger. The GM 4-71 is an excellent choice to get some more power out of your engine due to its commonality, low price point, and a plethora of knowledge and available parts for rebuilding. Originally utilized on the old Detroit diesels, these superchargers have been a favorite of hot-rodders since the 50s! Carburetors are spaced 4.800 inches apart on center utilizing 5/16-18 threaded holes for mounting. This piece is cast of 319 aluminum and wears the Nystrom script in the center. Carburetors and supercharger not included.