I'm about to buy an 87 K-10 longbed with a 4" Skyjacker lift. Easy questions first. What's the best way to determine the axle ratio on these? What kind of mileage can I expect with the TBI 350/700R4 combo? Also, I occasionally need more payload capacity than the typical half ton can offer. What's involved in upgrading to a 3/4 or 1-ton setup?