They used a pair of different ones, a 2-door and a 4-door, but both are standard M998s. Since the film is a 1991 event, you've got to make sure you use earlier HMMWV shots (no shoulder seat belts, original style mirrors) rather than later HMMWV interiors with better seats, shoulder seat belts and the truck style mirrors. Although this shot of the stills of both HMMWVs show the 4-door to be a later version with the different mirrors.
www.imcdb.org/movie_120188-Three-Kings.html
I've got some interior photos of various HMMWVs here.
www.armorama.com/.../albup58
Some decent undercarriage shots from this fender bender.
www.armorama.com/.../album71
Here's a later 2000s HMMWV with an aftermarket hardtop
www.armorama.com/.../albuu27
More photos of the interior, but focused on the various radio racks
www.armorama.com/.../albun64
And some walk around shots of a heavy HMMWV (load increased from 1 1/4 ton to 2 1/2 ton)
www.armorama.com/.../albuq92