I want to do a gear swap in my 54 GMC to improve highway speeds and gas milage as well, but I read some where that there are not kits available for the GMC rear end. Is this true? Also is there an easy way to ID what rear end is in my truck? The PO had already switched the Engine to a 261 and the hydramatic to a SM420, so he may have changed the rear end as well.
