The 700R4 is an automatic overdrive transmission.If you have a C30 you probably have a very high rearend,probably somewhere around 4:56.Anyway you can get that rear gear down to maybe a 3:42 will help on mileage,or better yet a 3:08.With the 700R4 it is about.78 to 1 ratio,whereas a regular 350 or 400 Hydramatic is 1 to 1 ratio.
