'88-'99 OBS Chevy Truck & SUV Seat Swap Upgrade Guide (GMT400)

What exactly is a GMT400?

"GMT400" is General Motors' internal platform designation for their highly popular line of full-size trucks and SUVs, affectionately known by enthusiasts today as the "OBS" (Old Body Style) generation. If you are searching for interior parts, this platform covers a massive range of iconic vehicles:

Chevrolet Models:

1988–1998 Chevy C/K 1500 Pickup Trucks (Silverado, Cheyenne, Scottsdale)
1988–2000 Chevy C/K 2500 & 3500 Pickup Trucks (1999-2000 badged as "Classic")
1992–2002 Chevy C3500HD Chassis Cab Trucks
1992–1994 Chevy Full-Size Blazer
1995–1999 Chevy Tahoe
1992–1999 Chevy Suburban

GMC Models:

1988–1998 GMC Sierra 1500 Pickup Trucks
1988–2000 GMC Sierra 2500 & 3500 Pickup Trucks (1999-2000 badged as "Classic")
1992–2002 GMC C3500HD Chassis Cab Trucks
1992–1999 GMC Yukon
1992–1999 GMC Suburban

'88-'98 GMC Sierra & Chevy Silverado Seat Options

1988 - 1994 Seating Options & Color Swatches

(Pre-Interior Update)

Applicable Vehicles

1988 - 1994 Silverado 1500 / 2500 / 3500
1988 - 1994 Sierra 1500 / 2500 / 3500
1992 - 1994 Suburban, Tahoe & Yukon

Available Materials

The base work truck trim featured an economical, highly durable vinyl. The base cloth was a tough, heavy-knap material built for utility. The Custom Cloth and Velour featured a much softer, plush material with the patterned inserts characteristic of early-90s styling.

Available Colors

Garnet - Red
Navy - Blue
Saddle - Tan
Slate - Gray

Available Features

Solid Bench Seats
Low-Back Bucket Seats
Manual Track Adjustments
Manual Lumbar (on select trims)

1995 Silverado Interior Color Options Seats

1995+ Seating Options & Color Swatches

Applicable Vehicles

1995 - 1998 Silverado & Sierra 1500
1995 - 2000 Silverado & Sierra 2500
1995-2002 GMC C3500 Chassis Cab
1995 - 1999 Suburban, Tahoe & Yukon

Available Materials

The work truck vinyl remained the standard for base models. The custom cloth received a more modern, tighter weave and pattern. The Custom Leather option became highly popular in this era, featuring supple, thick leather seating surfaces alongside durable vinyl on the sides and backing.

Available Colors

Neutral - Tan
Medium Gray - Gray
Dark Red - Burgundy / Ruby
Blue - Navy

Available Features

Low-Back Bucket Seats w/ Adjustable Headrest
60/40 Split Bench with Fold-Down Armrest Console
Six-Way Power Adjustable Driver Seat Track
Power Lumbar (Available on Custom Cloth & Leather trims)
Manual Recline

The Truth About Sourcing Original '95-'99 Seats

f you are a purist trying to track down a pristine set of original seats for a late-90s GM truck, you already know it is an uphill battle.

The Foam Problem: On the 1995-1999 cloth seats, GM manufactured them by gluing the upholstery directly to the underlying foam cushions. Because they cannot be separated cleanly, simple upholstery repairs or cover replacements are nearly impossible.
The Unicorn Leather: Factory leather options from this specific era are incredibly rare to find in decent condition on the used market.
Hidden Frame Damage: Even if you find a set of OEM seats with flawless upholstery, you have to inspect the metal beneath. The factory seat frames from this generation are notorious for structural failures and broken welds over time.

Because custom-building or extensively repairing these older seats is incredibly expensive and labor-intensive, most builders are turning to a much better alternative.

GMT400 Silverado & Sierra Interior Upgrades

2014-2019 Sierra Silverado Console to Jumpseat Conversion Kit, Black Leather OEM

Upgrading to Newer Generation Seats

Ditching the tired factory seats for something out of a newer generation is the most cost-effective and popular upgrade for an OBS truck today. Moving to a newer model seat can greatly expand your options.

Are they direct bolt-in?
Newer generation seats do not share the GMT400's flat floor bolt pattern, but the aftermarket has completely solved this. Using specialized adapter brackets—like the popular retrofit kits from Dan at OBS Outpost —you can seamlessly bolt a wide variety of newer, safer GM seats directly into your classic truck. It eliminates the need for cutting or welding, and usually comes in at a fraction of the cost of a full custom interior build.

OBS Outpost can produce brackets allow you to use a variety of seats in your GMT400, but you'll want to shop based on whether or not you need TWO matching seats, or a full set!

Complete Interior Swaps Available

Chevy Silverado (1999 & Newer)
GMC Sierra (1999 & Newer)
Chevy Tahoe (2000 & Newer)
GMC Yukon (2000 & Newer)
Chevy Suburban (2000 & Newer)
GMC Yukon XL (2000 & Newer)

Front Bucket Seat Swaps Available

Chevy Camaro (2010 & Newer)
Chevy Colorado (2015 - 2022)
GMC Canyon (2015 - 2022)
Cadillac ATS (2013–2019)
Cadillac CTS (2014–2019)
Cadillac CT4 (2020–present)
Chevrolet SS (2014–2017)
Pontiac G8 (2008–2009)

99-06 Sierra Silverado Front Seats, Dark Pewter Leather, Power Lumbar Bolster

Wiring Power Seats Into Older Trucks

If your GMT400 came with manual seats and you are swapping in a newer power seat, it will not be plug-and-play. Low trim level OBS trucks did not come pre-wired for power seats.

You will need to run a dedicated power and ground wire to the seat harness to get the tracks moving. If you are swapping in late-model heated or memory seats, you will likely need a ignition-on wire as well.

1995-2000 GMC Sierra Chevy Silverado Seats Set, Neutral Tan Leather Extended Cab

Bench to Bucket Seat Conversions

Needing a little more lateral support or wanting to add a center console for extra storage? Swapping from a solid bench to factory high-back buckets and a center console is straightforward.

The four outer bolts closest to the doors are identical. For the four inner bolts (closest to the center console), the GMT400 floor pan typically has the indentations where the factory would have drilled. You will need to drill these inner mounting holes and use heavy-duty backing plates or large washers to safely secure the inner tracks.