As far as your rear axle it could be a Bendix or a timken. On the timken the modle # will be on the top of the axle forward of the pumpkin on a flat spot. That #will give you the gear ratio's. Your truck wasn't made to go more than about 55 mph. The wheels and tires aren't balenced and will vibrate and that truck isn't going to stop very fast even unloaded. If you want more power get a 261 c.i. it will bolt right up to your bell housing and motor mounts. Adds about 10 h.p. in stock form. Add headers, dual carbs and a mild can and you will have all the power the truck needs. Remember, the gearing was very low in those big bolts for a reason, they were made to work, not Cruse the freeway.
