There may have been more aftermarket selections back in the day but the only one that I know of currently for TF trucks is the 3.36 gear set. According to my "1956 Task Force Engineering Facts Book" the only factory ratios available tor a 3100 and 3200 were 3.90:1 and 4.10:1. Possibly 57's had something different but I don't have any reference material for them.
There was a 3.07:1 rear end ratio available For GMC 1/2 ton trucks of that era. However, it is a completely different rear end assembly from the aforementioned Eaton rear end. The housing is different, the gears don't interchange, and even the brake drums are different. Probably not a lot of them left in captivity. I think something similar was available in some 59 Chevy trucks that were ordered with positraction.
Fred
