gear ratios

whats a quick way to find out the gear ratios in the front, rear and tranny?
she's a 74 with dana 30 / 44 D20 t-case and what i beleive is a t15 3spd. Can anybody tell me the original ratios? Thanks.

 

Default axle ratio in '74 is 3.73, option is 4.27. You'll probably have to open the cover and count teeth to be sure.

T15 has 3.00, 1.83, 1.00 with a 3.00 reverse gear.

Dana 20 is 2.03 low and 1.00 high.

One source follows:

http://jeep.off-road.com/jeep/article/articleDetail.jsp?id=277032

 

Only count teeth as a last resort. There should be a metal tag under the cover bolts on both the front and rear axles. This will tell you the axle ratio, the Jeep PN and the tooth counts. If there are no tags, take the cover off and look at the edge of the ring gear. The tooth count is stamped in the ring gear, ie "41 11" is 41/11 = 3.73.

 

The only way to know what you have is to pull the covers and read the ring gear. Remember that these Jeeps are all 30 to 60 years old and have had many owners. If buying a Jeep you need to pull the covers to check what is in there. Many factors need to be checked. Is there oil and is it in good shape? (I have seen one filled with sawdust to mask gear or bearing noise) Has the Jeep sat and let the gears rust? In areas with high humidity cases can rust very quickly if allowed to sit. Has someone welded up spiders or a broken case( Lincoln locked) Do the gear ratios match front and rear-very common on a project Jeep to mix and match parts while planning to swap gears later. I know your question wasn't neccessarily about buying a Jeep, but these things all need to be checked before going out on the trails anyway.