Daniel, por lo que he leido en paginas gringas seria:
Common gear ratios from '72-'75 were 3.73, from '76-'79 were 3.54, and from '80-'86 were 2.73.
Fuente:
http://www.jeeptech.com/axle/d30.html
The CJ-7 featured a longer wheel base than the CJ-5 and lacked the noticeable curvature of the doors previously seen on the CJ-5. It was introduced in 1976 and 379,299 were built during 11 years of production.
The CJ-7 featured an optional new automatic all-wheel drive system called Quadra-Trac, as well as a part-time two speed transfer case; an automatic transmission was also an option. Other features included an optional molded hardtop, and steel doors. The CJ-7 was also available in Renegade and an upgraded Laredo model. Noticeable by their different body decals, the Laredo model featured nicer seats, steering wheel tilt, and a chrome package that included the bumpers, front grill, and mirrors. An optional Trak-Lok differential was available for the rear.
Ring and Pinion was typically 3.54, but later went down to 2.73.
Fuente:
http://en.wikipedia.org/wiki/Jeep_CJ7#CJ-7
En todo caso lo mejor es hacer lo que dice Gonzalo, con la Hilift levantas atras y para una o dos vueltas de rueda cuentas cuantas vueltas da el cardan.
Saludos