Tom,

Assuming you have the following:

34" tall tires
6.17 rear
1:1 trans ratio (stock trans)

To reach 60 mph the engine will be spinning at 3700 prm.

If you add an OD trans with a .8 ratio the rpm drops to 2960 at 60 mph.

Hope this helps,

Mike B smile




Mike Boteler

1956 Chevy 3100 Resto Rod
1952 Willys M38 Army Jeep
1983 Jeep CJ7 Laredo
1984 Jeep CJ7
+++++
Silver Spring, MD