stay with the original side mounts out of a 63-66 truck with a six cylinder on of them is a diffrent shape than the other, with a v8 they are both the same shape so stick with the side mounts as the frame already has the holes where it mounts up as far as a front mount the engine block must be the specific kind that has the mount holes for the horseshoe mount in the front of the block but you will find out that there are 2 different styles of engine blocks so keep the tranny mounts and aquire some side mount perches for the frame. or upgrade to a newer block style as in 63-66 as this is a bolt up application without the hassles of making new mounts.