0.70 X 3.73 = 2.62 (tall final drive, probably too much for the engine)
I checked the Rear Axle Code on my '72 C-10 today.
It's an RHC which means 3.73 as figured.
Now on top of this, I put 265/75/15's on the back to help change the Ratio some.
How much trouble am I in now? lol