Hi. I have a 69 Firebird HO with 4-speed Muncie, block code WN. I had to have the engine rebuilt and the the shop found that the crank was wobbling due to poor prior engine rebuild. They said the block can't be rebuilt due to excessive wear. I located on-line a same year HO block but it was from a automatic car, block code XC. A buddy of mine who has a 69 Camaro said the block from the automatic can't be used with a standard tranny due to the need for a clutch bracket assembly requirement which needs the correct bolt holes in the block. Are the Pontiac engine blocks also the same and need special holes for the pivot bracket, etc? I really want to keep this car as close to original as possible and use the same block casting number (both the XC and WN blocks have same casting number. Thanks. John