Ford simply does not explain a lot of differences in GCVWRs on the trucks. I originally suspected differences in wheel/tire combinations, as that limits a lot of the superduty trucks, but I find no evidence there (but lots of errors in the wheel weight ratings). I have also come to the conclusion that the transmission and engine oil coolers included in the 53A possibly along with the stabilizer bar account for the different GCVWRs and trailer tow ratings.