I have changed both my '49 1 ton platform and '50 1 ton panel by changing the pumpkin assembly to a '72 4:10. It was very easy, strictly bolt in and only took about an hour and a half. With the GMC 248, I now can cruise happily at 65 MPH in the '49 platform. the '50 panel has .73 ranger overdrive with a modified 302 and has no problem doing 75 MPH all day.
