an r151f is a common tranny, i have one, however there arent any lower gears availiable for these, what we do is lower the low range gear set in the transfer case and axle to achieve a lower gear ratio. if you have a 151f then you may have a common transfer case that has parts availiable for it, or you could just buy a gear drive case from marlin built with lower gears as it will bolt up to your 151f easily.
Now we are talking
. And how do i figure out if i have "common transfer case" in my truck?
About tranny, thats what vin -plate says:
