We had a JD 4830 sprayer, and now a JD 4038 sprayer (sometimes confusing numbers!). We bought a "Greg Smith Equipment Sales" (Indianapolis, IN) jack stand & it has worked well for us. No problems. Realize it is a jack stand, not a jack. When removing wheels from the JD sprayer, you release air from the suspension while you have 1 jackstand under that axle...not the wheel motor, but the axle on the frame. A typical size shop hydraulic jack is then used to lift the wheel off the ground using JD supplied wheel jacking bracket (all air is gone from suspension now) & remove wheel. This is how JD recommends it being done in their OM. So, you use one tall jack stand to lower the axle onto, and one standard jack to raise the wheel assy off the ground. JD also sells a jackstand thru their parts for this, but I believe it's nearly $1000. The Greg Smith stand we bought has a 12,000# capacity and is adjustable via 2 methods. First, there's the obvious pin height adjustment, then the top portion also has a threaded sleeve you can spin with those handles. It's a fine thread (not Acme) that will raise the pad for more precise adjustment.

Ours works fine. I'd buy another if we needed it for some reason. The caster wheels have springs & compress easily, but will extend again with no weight on them to allow easy movement of the stand assy. Looks like Greg Smith gets $379 plus shipping. I'm sure it's a "common carrier" item. They seem well built to me. Welding on them looks very substantial. Here's link to Greg Smith Equipment:

http://www.gregsmithequipment.com/12-Ton-Vehicle-Support-Stand

Here's photos of our stand. It's under our 4830 in the photo. I did take one of the Smith supplied pads & modified it to fit under the JD axle. You can see that in my last photo.