I wanted to know what I should do about that low gearing in the rear axle. I want to be able to do freeway speeds. I have seen several trucks like the 6400 converted to go much faster than 55mph. Will I have to put in a more modern rear axle with higher gearing, or can I alter the gearing in the rear axle and keep it original? The rear axle is original. It looks like it came off of a semi! The reason I like these trucks is they are so overbuilt. I am really leaning towards converting the rear axle. I don't want to swap axles. Is there a way I can keep the original rear axle, but still be able to go about 70mph? When you are running a buisness, time is money. I will lose alot of money if I cant go over 55mph.
