light duty htransmission translates to what

[hillcountryflt]

My VIN indicates my 71 F100 has the light duty 3 speed with three on the tree. What is the actual model/make of that transmission and since it has the highest gear ratio rear-end (based on the VIN) what model would that be. Would like to read up more on servicing these items and might help to know the actual models here. Someday the three on the tree will become an auto, but I am thinking that is a ways away.

[HIO Silver]

According to Fordification's tech articles, VIN Code C is a "3.03".

http://www.fordification.com/tech/transID-man.htm