I find it helpful to pick the heaviest vehicle you have (the driver's door jamb should have a label giving kerb weight and GVWR...) then pick stands so that each pair can hold that weight. Two pair (if you have to lift the whole thing) should therefore not be a problem.
Jack ratings should be done similarly - you're only picking up half of the vehicle at a time, but it's nice knowing you're not anywhere near the limit. The lowest I'd go on a jack in one-and-one-half times the weight I expect to pick up (heaviest axle * 1.5 - GAWR figures should be on the same label, and the front axle is typically the figure I use - unless I'm planning on picking up a loaded truck...)
Can larger stands be had? Certainly - jacks as well. While I was doing the "industrial wrench" thing, the work truck had the following:
- 8-ton hydraulic bottle jack
- 10-ton mechanical "ratchet" jack (damn thing was made in 1942. We had it X-rayed every year, and kept records of it.)
- 10-ton jackstands, three pairs
- 6-ton hydraulic "floor" jack
- 5-ton "airbag" jack
I wouldn't get anything from Harbour Freight - my usual rule is "more than my body weight? Get it somewhere else." I've had good luck with stuff from Northern Tool & Hydraulics (
www.northerntool.com, I think) and there are other suppliers as well. If you want something solid, find out what shop caters to the "heavy truck" mechanics locally, and shop there (for instance, if you're in Santa Clara County I tend to recommend Specialty Truck, near Gish Road in San Jose.)
What's wrong with Harbour Freight? Most of their heavy stuff is made in China - while Chinese steel isn't too bad (most of it came from the scrap market over here,) they still haven't gotten the hang of heat treatment. The rest of the Pacific Rim is fine - but they either learned from us or from Germany. If I'm going to put more then 250# on the thing, I'll get it somewhere better - it's usually worth the difference in cost, believe me!
