There are several methods that have been done by folks here.
I just took an 8" (or so) stove bolt, inserted it into the stock spare tire holes from the bottom, put a nut on it from the top,
put a spare poly eurithane shackle bushing over it, put the Hi lift onto it & put a big washer & some big wing nuts on the bolt.
I need to devise a lock for it though..
which do you mean, the angled one or the vertical one?
I mounted mine on the top of the angled one by putting a piece of threaded rod through the lower hole meant for the spare tire holder, putting locknuts on the rod on either side of the rollbar to rigidly mount it.
Then I used another locknut and washer as a lower stop, slide one of the holes in the jack over the threaded rod and then use a short piece of heater hose, another washer and locknut to tighten down a little on the jack.
I store a couple of rags under the foot of the jack to keep the bottom from rattling around and use a bungee cord around the jack and rollbar right near the bottom to hold that end in place. I also put a hose clamp around the "bar" and handle to keep the handle from rattling.
Cost all of about $4 and you'd never know it was there... not one rattle.
Look on the left side of this pic (I was using duct tape on the handle at the time)...
Thats what I had in mind. Mounting it on the angled down tube going over the wheel well. It will need to fit under the full top too. I don't want to mount it on the outside for a couple of reasons. Theft for one and chiping it out of a block of ice at -40 here in Fairbanks... :-(
FWIW a 48" hi-lift will fit directly behind the front seats and the stock console. Mine has been there for years and it doens't move anywhere and it protected from the elements. I noticed that hi-lifts that aren't used much, are left outside and aren't lubed regularly get locked up and are hard to use. So I wanted to keep inside....
mines on my roll bar down tube, the weather does get to it but if you wheel without some extra Lube around your asking for more than a stuck HI-Lift....anyways i used some 3/4" thick bolts i found on the farm that were about 6" long. cut the heads off and weled one up close to the Mian bar then down near the foot of the downtube and ground the ends of the bolts so the oblong holes to the HI-Lift sat right down over the ends of the bolts. all you have to do is have the washers that fit the bolt snub and weld them up where you wnat the jack to sit and then make sure the jack slides down far enough over the bolts that you can drill a hole int he end of the bolt and put a lock in it. Works like champ!!!
You can kind of see what i'm talkin about here in this pic...i'll post another