Doogie - they were indeed. I didn't make them, I bought them off ebay for $70 odd dollars.
At the end of the day, it is just lengths of angle cut and welded with marine ply top tech-screwed on
The only ones I have seen for sale have been in the UK not out here and cost several thousand dollars:
www.restorationramps.co.uk
They have a version which have scissor-lift jacks either side which enable you to raise the car up and remove the wheels whilst on the ramps
smac - the works BMC team in england developed a quick lift jack for endurance races (spa 24hr etc) which used two lifting points below the bumper (but the bumper mounting points) and a portable trolley much as you described. There is a photo in at least one of the Brian Moylan books I have at home.
Several people have asked for plans or do I sell them - The answer is no. I have no way of producing autocad type drawings but if someone here has, I have no objections to someone coming out, measuring it up and producing autocad type plans provided they publish them here as pdf's for all to share.