I worked with Wagner CAT in Aurora to get Oscar up to speed. I thought I had a line on getting the gears for $500 each through a scrapyard near Brenham, Tx… They sold the last set a week before I called. The CAT shop found this new set of 307’s to get me up to near 70 mph on the road. The cost was almost 5x’s that of the gears out of Texas, not including installation.
If you are looking to get some gears done on an LMTV there is a very informative post here that will get you up to speed (no pun intended).