This is the second version of the 6.5 7.5 series front housing for the 15mm crankshaft. Several versions were made of this. This uses a draw bar to hold the carb/venturi. Some versions have a sprial in the of the crankshaft bore between the intake and front bearing. Some had a vacuum hole between the front bearing and intake. This has neither but should fit parts from any of the 15mm crankshaft housings. Carb neck diameter is .625"

15mm Crankshaft Diameter - Requires drawbar 28-8701