When you see a big American pickup truck wearing a dark exterior finish with brown stripes and aftermarket add-ons, the late 1970s often comes to mind. This custom truck originated over a decade after disco, but we wouldn't blame you if you had trouble recognizing both its era and origin. It's really a 1990 GMC Sierra 3500 dually, and if you dig it, you can buy it right now for the tidy sum of $19,995.

This extremely custom pickup is currently listed for sale at ClassicCars.com, but it's not a weird one-off widebody conversion built in someone's backyard shed. Knudsen Automotive Design (now Rage Exotic Vehicles) created a range of kits through the 1980s, including the Tridon body kit seen here. The Sierra already had a wide backside with its dually design, but there's no denying the dramatic widebody look from those Testarossa-themed side vents flowing into the rear quarter panels. The front fenders also grew in width, and the pointed nose completely disguised the flat face shared by GMC and Chevrolet pickup trucks of the era.

Gallery: 1990 GMC Sierra 3500 Tridon Conversion For Sale

Photo Credit: ClassicCars.com

As for this particular rig, it's listed as being in good overall condition with 60,000 miles showing on the odometer. The paint is obviously in rough shape, and there are some blemishes in the fiberglass body kit. Underneath is a different (and better) story with a plethora of mechanical maintenance performed in the last 15,000 miles. The tan interior is said to be flawless, and judging by the photos (more of which are available at the listing) we're inclined to agree. Under the hood is GM's old 454-cubic-inch (7.4-liter) V8 connected to a three-speed automatic transmission, driving the dual rear wheels at the back.

$20,000 certainly isn't cheap for a 31-year-old one-ton GMC Sierra, especially with this truck apparently being rear-wheel-drive only. However, the listing states the Tridon conversion was a $12,000 option back in the day, and with this rig having just 60,000 miles, it's hard to say if you'll ever find another example like this one.

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