3875744N is the correct casting number for a 1966 10 bolt housing. The spring perches on a 66 housing can also be identified because they are flat and have two bolt holes in them.
66 El Camino 396/325HP 4-Spd
My Build Thread:
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
62 Corvette 327/360HP (original RF engine and Fuel Injection) (future restoration project)
66 Corvair My son's project. Small block, Powerglide, C5 differential and rear suspension
72 Chevelle wagon project