Welcome to the forum and thank you for your service, shane! Axle-wise, a '72 4x4 model would have been originally equipped with a Dana 44 rear and a d30 front with drum brakes all around. You can do a google image search for both d30 and d44 axles and compare to what you have up front. The shape of the gear housing and cover is very different between the two. Also, an sii d44 front will almost always have disc brakes, however there were some 44's that did come with drums, just as there are rare cases of d30 front's with discs, so the brake hardware isn't a 100% identifier. '74 was the transition year for sii front driving axles, with some cross-breeding mixed in just to liven things up for us nearly 40 years later.
As for discerning the gear ratio, check the diff cover's for any small, tin tags. Often those disappear or get trashed beyond recognition, but you might get lucky and find one that is still legible. If not, you can remove a diff cover and you will find a series of numbers stamped into the ring gear. One of those numbers corresponds to the ring gear teeth. Another one is for the pinion gear. Or you can count the teeth of the ring gear and divide that by the number of pinion teeth. For example, 46 ring teeth divided by 13 pinion teeth is a ratio of 3.54 to 1. The main thing of course, is that your ratios are identical in both diff's.
. Found the board searching for parts from a genuine light line dealers search on google, I don't know much about IH's or scouts for that matter but I am steadily learning.
