it is in the same relation to the engine regardless of the rest of the chassis

They are coped at 1 inch to fit standard size frame tubing

The CE-8188 will fit as stock replacement on 1981 - 1988 Harley-Davidson Big Twin Models

which is nice

and bolt the tank down using some leather washers to cushion between the gas tank tabs and the frame

Crankcases 1941-1947 Harley-Davidson Knucklehead - Replaces OEM #24520-41 Thread Size_3/8-16 it is in the sameReproduction crankcases which meet or exceed highest restoration demands. Cast from state of the art materials and machined on CNC equipment for strength and precise fitment. Intended to work with stock or identically constructed engine components. Finished and detailed like the original counterparts so these cases will smoothly blend into your old mill to give it a new life. For ease of installation both case halves are carefully matched and feature