hey, I have a '76 K-5 Blazer and the last owner said he had 3.73 gears installed but he couldn't remember if they were higher or lower from the factory. I am needing to figure out what carrier it has, the 3.73-up or the 3.4?-down. Anybody know what codes I should look for on the carrier itself or anywhere else on the truck? If it had an RPO list it has since been painted over...I think he had a Maaco job and they don't believe in taping things off. Anyways, I'm running 35x12.50's and it's a little doggy on the highway. I was thinking of switching to 4.11's so I can retain some fuel mileage with the 350/350 combo. PS. Anybody know the case length and output shaft differences between a th350 and 700-r4? If I could do a swap then 4.56 gears would be grrrrrreat.