Yes, I'd say you have a dilemma. 4.83 sounds outrageous, but keep in mind that's with 35's, so it's not as drastic as it appears on the surface. Probably not a whole lot different than 4.10s with a stock tire dia. Also, keep in mind that with those tires and 4.83s, your speedo is totally out to lunch, so any speed vs rpm comparisons should be made with a GPS. Anyway, here's a chart to help you kinda see what benefits you'd get from a gear change alone, trans change alone, or both. 700R4 is shown, but NV3500 is .73 o/d rather than .70, so it gets you in the ball park at least. Note that TH350 with 3.73s (i.e. gear change only) nets you 1969 rpm at 55 mph whereas a 700R4 with 4.83s (i.e. trans change only) puts you at 1785 at 55. So, considering it's 4WD and the cost of both gear changes as you've highlighted - I'd say it's worth the relatively small "extra" cost to do the trans only - and you will maintain your rock crawler capability with the NV3500's low gear (might want to consider an NV4500 for strength) and still have the ability to cruise at decent highway speeds. Note that o/d + a swap to 4.10s (middle chart on right) puts you at too low an rpm at 55 mph to use 4th (in a 700R4) or 5th (in an NV3500) (so you'd cruise at 55 in 4th and 65 or above in 5th). I think this makes the case that you can achieve your goal with a trans swap only. Both might be overkill with negative results - I'd sink that potential extra gear cost into beefing up the new trans. Sorry, 700R4 numbers the only ones I had handy, would have to break out my excel geek bifocals to dig in and add a 5th gear to the chart...
