O.S. Crankcase 21XZ-B Spec 2Tower Stock# OSMG4239 • Manufacturer Stock# 22421050
Notes from our tech department:
O.S. Speed Tuned 21XZ-B Speed Spec II Engine, OSMG2052.
Constructed of aluminum, anodized flat black in color
Crankcase for the O.S. 21XZ-B Speed Spec II Engine
Installing all engine components into and on crankcase