Surfblau, I bought the compressor from Princess Auto in Canada at a sale price. They have a web site,
WWW.princessauto.com. They have an on-line catalog, but I haven't looked at it. The prices are likely Canadian.
I did'nt feel unsafe using the compressor. Each hook matched the coil angle reasonably well, nothing slipped, and there were no scary noises.
The compressor should be installed with the wheel hanging freely to open up the spaces in between the coils. Very important to leave the shock attached at all times because that's all there is holding the spring in place. Try to hook the compressor on the lowest coil possible to spread the compression over as many coils as possible (as in my first pic).Then once the compressor is installed, raise a jack right under the lower control arm (W123 in my case) at the coil spring to compress it. This will save some time and effort cranking the compressor. Then it's not too much cranking from that point. Then remove the jack.
Here is a pic of what I used: The string is to lower and also retrieve the compressor from the top. The flat washer went on the top of the spring tower from engine compartment.