Read the alternative fuels section of this site. Got some good info there and there's a long post about using biodiesel in the 6.2L.
I don't drive my CUCV pickup daily but I have when my DD has given me trouble. Sometimes for a few weeks actually. It's not bad but you have to remember it's a bare bones truck with minimal sound insulation, a LOUD diesel engine, no radio, no over drive, and even when new the wind noise on these things was horrendous. Oh, and the steering was terrible as well when they were new. If you're lucky it's still terrible and not any worse. You get used to it.
Which CUCV are you looking at, the pickups or the Blazers? Honestly the pickups are beefier with their 1 ton axles but the Blazers would be a better daily driver due to their 3.08 gears.
Pickups have 4.56 gears which is very low geared for the 31" tall tires they came with. However recent reading of my -10 "owners manual" shows that the military considers their max road speed to be 37mph...so they don't care about the rpm's. Convoy speed is 35mph so they never expected these things to crank out 70mph or even 55mph. I had one up to 50mph once on the stock tires and it sounded pretty scary. One solution is to find someone with a similar civy K30 and swap them for their lower geared axles if you want to keep the little tires (beware their vehicle WON'T have a locker in the rear (all pickups) or a limited slip in the front (M1028's only) unless they put it there from the aftermarket). 3.73 and 4.10 gears are common in civy K30's.
The other, and arguably easier, solution is to put taller tires on. Even 33's would give you more top end speed for the pickups. However some of us have shown that you can run 36" tires on these at the stock height with some rubbing that isn't horrible if you do minor trimming. My truck's future includes about 1" of front lift and enough trimming to keep the tires off of the fender completely.
Mine goes down the road pretty well with the 36's and 4.56's but it still is kinda low geared. OD would be great as well. Something to consider for the future.
Now with a Blazer you'd have 3.08 gears which if anything are high geared...but you could likely do 70mph all day with that setup even with no OD. However there's likely oodles of people with 3.55, 3.73, and 4.10 geared half ton axles ready to dump them for 3/4 ton or 1 ton stuff so you can relatively easily upgrade to better gear ratios.
