I would be cautious about that "steering needs work" statement. It could have a separate hydraulic pump (most TLB's do) that is going out so it could be a grand or more just in parts. Keep looking and you might find something a bit newer and in better shape. Buying used presents more issues for repair and I certainly wouldn't want to buy something that I had to repair before using. As already stated, look for Case a there will be more parts availability for it. Cat is good but parts will be much higher IMO. 4 WD would be a plus but for those big machines, even 2 WD do a pretty good job.
For terracing, I would look at contracting a dozer. A backhoe can dig and haul ok, but for moving and leveling a large amount of dirt, you cant beat a dozer.
Culvert must have been too small to have washed out. Look at the wash out size and size your culvert accordingly. Put lots of rocks on the upstream side to control the flood water and keep from washing out any more of your road. You may also want to put some larger rocks on top of the roadway, just in case your culvert doesn't contain all the water and it washes over the road. Larger rocks OR a concrete cover will keep the road from washing.
