Is there a part number on the bottom side of that manifold?
There are six different dual Port manifold for the small block Mopar.
6005 DP is for the 340 360 standard 4 Barrel
6006 DP is for the 340 360 with the Quadrajet spread bore
6020 DP it's for the 273 318 1966 and later with square bore
6021 DP is for the 273 318 66 and later with Quadrajet spread bore
6022 DP is for the 273 through 1965 standard 4 Barrel
6023 DP is for the 273 through 65 spread bore
Yours looks to be a 6006DP or a 6021DP to me.
