People can say what they want, and if you are splitting articulated machines you want something stronger, but for a straight frame tractor, you can build awesome stands quickly and inexpensively with heavy duty drop leg jacks.  I built a set last week, took about an hour.  I used two 5,000lb drop leg weld on jacks, welded a 1/2" plate to each after marking and cutting the holes from the frame bolts, and then welded fixed heavy duty casters to the foot.  Thor's look like swivel casters to me, but I used fixed ones so they didn't rotate and mess up my alignment.  I dropped the leg down one notch to where there was a hole exposed,. and then bolted a piece of angle at the base of each jack to keep them from even attempting  to spread apart/pull together when the weight was on them.  I sat a 1066 IH on them for over a week with no noticable strain.  I used a 6 ton jack stand under the rear with a 20 ton air/hydraulic bottle just snugged up against the underside of the tractor.  I probably wouldn't go much heavier than that without a stouter stand, but I would do that one and any smaller anytime with those.  I like the dual jacks, if anything shifts at all, you can use them independently to re-align when going back together.