Just bought a 17080507, looks to be unmolested, factory 0507 sticker still on and idle adjustment screw caps still sealed. It’s M4MC, 750 cfm with the additional screws in the airhorn, and single main air bleed, the build date is 3101DNR, so maybe it is an 81 model? Any one know what it came from, guessing GM truck, it has front choke pull off for secondaries, along with rear choke pull off for choke. The choke is hot air.