How Low Can I Go?

I have a 75 CJ 5 with 30/44. Currently geared 3.73. Can I go to 4.27 w/o changing anything else?

 

The D44 case break is 3.73. You'd need thick gears to use your existing case or get the correct case.

 

Yukon has the thick gears for the 44. Did not check on the 30. The 4.27 gears I did not see.

 

D30 break is 3.54/3.73 so he could use the existing case for 4.27.

 

Your best bet would be to find a T-18 transmission with the compound low first gear. I had that in a '75 with a 258. Good on the highway and good offroad with
the low first gear. I think i saw 90 once getting away from some semi's that were playing leap frog on me. The carburetor stunk on and today I would go to fuel injection
and a better ignition.

 

Yukon has a thick gear for the rear but not in 4.27. Standard gear in a D30. Cost and performance lead to T-98 transmission.