My 69 C-10 with 6 cyclinder and 3 speed automatic has a 3:73 gear which I understand is pretty much standard. I understand that the 3:07 & 4:11 were options. I would like to install a 200-4R and possibly a 3:07. If a truck had a different rear gear from the Factory it be listed on the SPID on the glove box wouldn't it? I know of a few trucks in the bone yard, most are not in a position as to where I can turn the rear axle to determine the ratio. Just how common is it to find a 3:07 rear end?
