Pre-02 monsters are "hooped" monsters, with a frame based off the 851/888 superbikes. the suspension uses a rocker, with a hoop on the wheel-side, that connects to the swingarm. When the wheel hits a bump, the swingarm rises, the hoop acts on the rocker, which pivots and compresses the suspension on the far side. Lengthening the hoop raises the rear ride height. This can be accomplished with an aftermarket hoop (no longer manufactured - unobtainium old-stock from Febur and Rizoma, etc) or with ride height
spacers or
adjusters. Another solution is to get longer heim joints, or rod-ends to accomplish this same task. (hello McMaster-Carr online catalog!)
Newer Monsters (2003-2009) use a single bar, which is used to adjust ride height. Most bikes do not come with an adjustable
ride height rod, but one could be had by purchasing a billet piece from a plethora of manufacturers. A longer or shorter one from a superbike series or other Ducati bike could also be swapped in to raise or shorten the rear ride height.
I've got the "classic" era Ducati Monster 900. Here's a pic of it with an OEM-length billet swingarm suspension hoop / arc / arch, and the stainless ride height adusters:
