51bolt,
I have a set of dollies that I got six years ago from Harbor Freight (I call this company my chinese warehouse). They are excellent, and they are sold by other companies also, and they can be found for around $100 for a set of four.
They dollies are completely safe to use while working under the truck (as long as your floor is level). Also, I can easily move the truck around on the dollies by myself.
I get a little extra height, when needed, by placing a 2"x12"x2' piece of lumber between the top reinforcement bars and I get about 4-5" extra height
Tim
Every so often these are on sale for $100:
Harbor Freight dollies
