[Robert1970C20rstbukt]

As far as shop manuals and literature goes, keep an eye out on ebay. I found an original service manual for my '69 GMC 8500 on there as well as an original owner's manual. My truck has a 7.17 gear ratio because it was ordered as a refinery fire truck, never left the plant so it didn't need to reach highway speeds. It can do about 50 but that's pushing the V6 around 3200 RPM's, way too high. I think the high range of a two speed is higher than that, but there are better gears for highway use available.