BB, welcome to the board...while I am a major fan of torsion axles for most uses, a really serious off-road tear should have a spring suspension since it gives more travel/articulation
...if you want a serious off-road unit, start with a 3500# axle with 2000# springs onit
...the reason
...the 3500 has a thicker axle tube and heavier running gear to start with
...used with lighter spings to give a better on road ride and possibly add shocks if you do a bunch of washboard or higher speed forestry or desert roads
...spring suspension will generally give you more frame to ground clearance
...it will also be easier to fix/find parts for if you bust it
...if you want a torsion axle, do the same
...get a 3500# axle and have them de-rate it to 2000#s and have it built with a pretty good down start angle
...what ever you do, take lotssa pictures 'cause you will want proof you built it and we wanna see 'em
...pictures are what we charge for more advice that you can use
...we luv da pics 'round here
madjack
...I have come to believe that, conflict resolution, through violence, is never acceptable.....................mj