I have a fullsize 1981 Ford Bronco in which I want to put lower gears in the differentials. It has a 302CID engine with an automatic transmission. It currently has 33" tires, but I will probably put a set of 35" tires on it. It still has the factory 3.00:1 gears (like an airplane with those 33's). I found a [url=http://www.4lo.com/geartable.html]differential gear calculator[/url], but it assumes the 1:1 final drive ratio of a manual transmission. What is the final drive ratio of my automatic? I cannot remember if it is a C-4 or C-6 transmission off the top of my head. Also, what type of front differential does it have? I believe it is a Dana of some sort. The rear one is a 9". Thanks!