Honestly a junk Yard Chrysler 8.25 would be the easiest, and probably most cost effective swap...chances are the gear ratio's will be the same (3.55 - stock) and it will bolt right in with ease...you're drive line may have to be swapped out as the distance from the yoke at the pinion center is different on the two axles.... worst case scenario you'll need to swap out a drive line.... Now, the 97 and older Chrysler 8.25's are 27 spline, not bad... but the better ones are from the newer model XJ's and those come with 29 spline axle shafts..... Either will be a good improvement/upgrade from the 35.... that being said... if this thing will never see a trail, or if you do VERY light wheeling, then the most economical solution will be to swap it out with another Dana 35.... be careful the doner axle came from a vehicle with the same kind of engine as yours...(this applies to the 8.25 as well) --- the 4cyl jeeps came with 4.11 gears... if you mis-match gears, you'll destroy your transfer case and or tranny.
Your only other option would be to rebuild the 35 you have...they do sell kits... new bearings, and seals, and you'd have to get the gears re-set (backlash/pre-load/etc) ....do some research, call around, get prices, and choose whats best for your budget and skill level.
Good luck - hope this helps.