The engine perches align with the rear holes on the upper flange of the frame. The 292 engine has a staggered perch, which is why there is an extra hole on the frame flange. If you move the engine forward, then the cast-iron bell housing will not line up with the crossmember for the bell.
Folks who install an LS engine in a 1963—1966 C10 usually move the engine forward a bit to allow clearance for the rear coil pack on the passenger side at the firewall. The same is true with folks who install a SBC with tall valve covers.
Last edited by Lugnutz; 04/08/2023 1:16 AM.
