I thought the H1 was pretty much the same vehicle as the real deal, drive train-wise. I know the H2 and H3 are softened up.
The H1 was close but the others were sheep in wolf's clothing.
I had the use of a real one in the early 90s. Would like to have it today. That critter was puurrrrddy.
The H1 has the drive train and suspension of the 'real deal'. It's the civilian version of the military Humvee. The H2 and H3 have the straight axles since, if I remember correctly, the H2 is basically a suburban with a boxy 'Hummer' type body. I figure the H3 is based on a blazer chassis.