I have a 83 Chevy c10 with a 350 and 350 auto trans. It seems to lag when i hook a trailer to it so i am thinking of a rear end gear change. Do any of you have an idea of a good ratio and some tips on putting them in. I don't what anything in the 4:10 or higher because of only having 3 gears it will get terrible gas mileage. I am thinking like about 3:23-3:73 is this right. Also while i have your att. it only does about 10 mpg. is this about right or is there something i can do to boost this some?