In 1991, it looks as though the 2-wheel drive Sport got the special red/black side mouldings, fog lamps, chrome wheels, black mirrors and body colour bumpers (with rub strip on rear bumper). The 4X4 Sport did not have side mouldings, but got aluminum wheels black coloured bumpers with no rub strips, mirrors and wheel flares.
The next question would be whether rub strips were available as an option on the front of the 2X4 and on both front and rear on the 4X4.
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2004 Z71 Tahoe 4x4 5.3L (factory white monochrome theme)
1989 Silverado K1500 4x4 5.7L sportside (white monochrome theme)
1967 Belair 2-door-post (project)
1967 Corvette 427/435 coupe (now 502/502
red road warrior)