I have used ATD tools at work and Hot Rod Garage in Sandsprings OK has a ATD-7325 low pro jack for use under very very low street rods. here is a link
http://www.atdtools.com/Tools.html. Our local semi truck and trailer parts store,Weldon Trk Supply, carries there stuff. You can also source it from the internet tool stores. I think it's pretty good stuff for import and priced right.