GMC C20 Questions

[lukecp]

My stepbrother has a '70 GMC 3/4 ton longbox he has been trying to sell me for quite some time now. I finally got to look at it and drive it today.
It is an original Colorado truck, so the body is really solid. Needs 2 rockers and a small part of one cab corner, above the windshield, floors, and cab supports are rock solid. Unlike my '72, which needs alot of work in all the commonly rusted areas.

Anyway, it has a coil spring Dana 60 in the rear. It is an orignal 307 truck, with a granny low 4-speed transmission. The original 307 is gone, replaced with a very well running 327 from a 1962 fullsize car (i verfied it with the engine suffix codes).

So, what would the axle ratio in the rear be stock? I'm thinking 4.10, but the truck seemed really low geared so it may be lower. I have the axle ratios for a C10 figured out, but C20s are a different ballgame.

Also, which model transmission would this truck have in it?

I want to buy it, and he said he could proably hold on to it for me for a few years until i can afford it.