you have the original axle 3B cites, the reason you don't get the 6.1 ratio is you need to turn the wheel twice, not once, that truck would have a hard time getting rolling with a 3.1 ... if in doubt take off the cover and count the teeth

Bill

Moved over to the Passing Lane

"When we tug a single thing in nature we find it attached to the rest of the world" John Muir
"When we tug a single thing on an old truck, we find it falls off" me
Some TF series details & TF heater pics & Rust-a-holics Unanimous parking lot