1989 GMC Jimmy - Decked Out

    Glenn Decker's Trail-Prepped GMC Jimmy

    Ken BrubakerPhotographer, Writer

    As is often typical in off-roading, each wheeling trip that Glenn Decker took in his 1989 GMC Jimmy was the catalyst for upgrades. A couple of axles here, a new transmission there, and pretty soon there were upgrades everywhere. But Decker, a stay-at-home dad/stereo system fabricator from Rancho Cucamonga, California, kept buildup costs down by sourcing many used parts. For example, he found a used Offroad Design Doubler for sale on an Internet site and a set of used 42-inch Swampers on double beadlock wheels for sale in Arizona.

    Also as is typical, the '89 Jimmy is an ongoing project. Decker says he plans to add an ARB Air Locker to the front differential, PSC hydro-assist steering, and possibly a four-link front suspension.

    A couple of axles here, a new transmission there, and pretty soon there were upgrades everywhere.

    We found Decker prowling around the southern California desert and we were impressed at his work thus far and his dedication to wheeling a fullsize rig. Decker has done a great job of decking out his rig.

    There’s all kinds of cool custom stuff going on in the back of the Jimmy. The most obvious is the custom tray that allows for safe, secure, multi-level storage. When we photographed the rig, Decker had a 60-inch Hi-Lift Jack, toolbox, Ultimate Air CO2 tank and some recovery supplies on-board. Normally there is a spare tire and wheel mounted on the lower level. The rear of the rig also features a custom rear bumper made from 1.750-inch-diameter, 0.120-inch-wall DOM tubing and it sports 1-inch-thick D-rings, and a 2-inch hitch receiver.

    At A Glance
    Vehicle: 1989 GMC Jimmy
    Owner: Glenn Decker
    Stomping grounds: Rancho Cucamonga, California
    Build time: 6 years

    Engine: GM Performance 350ci V-8, TPI, Doug Thorley headers, Magnaflow muffler
    Transmission: Modified TH400
    Transfer case(s): NP203/205 Offroad Design Doubler
    Low range ratio(s): 2:1, 4:1
    Crawl ratio(s): 22.6:1, 45.2:1
    Front axle/differential: Dana 60, Yukon 35-spline chromoly axleshafts, Warn manual hubs, ORD high-steer and crossover steering/4.56 gears, open
    Rear axle/differential: GM 14-bolt, Yukon chromoly axleshafts/4.56 gears, Detroit Locker

    Front: Deaver Suspension leaf springs, Rancho RS9000 shocks, polyurethane bumpstops
    Rear: Deaver Suspension 57-in leaf springs, Rancho RS9000 shocks, polyurethane bumpstops
    Steering: Chevy 2WD steering box, ORD pitman arm, ORD crossover and high-steer system

    Tires: 42x15.00-16.5 Interco Super Swamper TSL
    Wheels: 16.5x9.75 Humvee double beadlock

    Armor: Custom front bumper, custom rock sliders, custom rear bumper, custom rollcage
    Cool stuff: '94 Chevy Grille, custom cargo area storage, lots of exterior lighting, rock lighting, front-mounted Mile Marker SE 12000C winch

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