Doc, you won't get a good guesstimate that way, since the axle gears and spider gears might also get involved. With the truck on a flat surface, put a paint or chalk mark on one rear tire, and roll the truck straught ahead one turn of the rear wheels. Count the number of turns of the drivershaft for a pretty accurate idea of the gear ratio. The 5.40:1 ratio in the original post would result in almost 5 1/2 turns of the driveshaft. Putting a paint or chalk mark on the driveshaft or universal joint will help you get an accurate count.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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