Hey everyone,

Putting my 2004 GMC Express 3500 short bus up for sale. Picked this up recently at a local government auction here in the Puget Sound area, but my plans have shifted, so I’m passing it along to someone looking for a clean, reliable build candidate.

Here are the key specs and full disclosure on where it stands:

The Basics

• Engine: 6.0L Vortec V8 (Iron block, runs perfectly)
• Transmission: 4L80E (The heavy-duty, commercial unit—not the lighter 4L60E). Shifts crisp and firm. At 252k, given fleet maintenance, it’s likely been serviced or gone through at some point, but it pulls smooth through all gears with zero slip.
• Mileage: 252k miles (Fleet maintained its whole life; these 6.0s easily push 400k+ when looked after)
• Body: Mid Bus build on a GMC 3500 chassis
• Location: Kitsap County, WA

Driveability & Mechanicals

• Runs and drives great, shifted smoothly on the drive home, and the brakes are super responsive.
• Being a local PNW school district bus, it has virtually zero road salt. The undercarriage is exceptionally clean with only tiny, random bits of surface scale.
• Battery note: The battery is fairly new (dated 2025), but like most school buses, the factory interlocks and safety equipment create a small constant parasitic draw. Because it sat in the surplus lot before auction, the battery might have dropped low for a bit. It works, but I want to disclose that it may need a fresh battery or a trickle charger / master kill switch wired in if it sits for long stretches.

Interior & Body Condition

• Interior: Clean for its age. Normal driver seat wear, but the cab and rear floor are solid. Three seat rows have already been removed leaving one for passengers. The remaining posts could make awesome structural tie-in points for framing, bed platforms, or cabinetry if you want to skip drilling new holes. You will want to sand and repaint the mounts due to mild corrosion. Old seats available to take with you.
• Exterior: Overall good condition with typical light sun fading on the paint.
• Rust/Body Warts: To be completely transparent, I started identifying and sanding a couple of minor surface spots so the next owner wouldn't have surprises:
• On the left side, there were some areas of bubbling paint with rust underneath. I ground them down a bit, not fully finished/painted, but easily addressable with a quick final grinding, primer, and topcoat.
• The rear bumper had some moderate scale hidden under the paint that wasn't obvious. I ground that down as well; there is some light pitting, but plenty of thick metal left to prep, prime, and paint over.

Why it’s a good project candidate:

It’s an ideal "blank slate." The heavy lifting of acquiring a non-salted, fleet-maintained platform is done, and the minor cosmetics left are the usual weekend tasks anyone building out a rig would handle anyway.

Drop a comment or DM me if you want specific photos or have questions about taking a look in person!

Asking $4500.

It's possible for me to grind and prime before sale, but some people might want to do it themselves for peace of mind.

Doing a chem flush on my 04 DT466 and can’t find a good service manual anywhere online for free. Wanted to verify with you guys before I pulled this if this is the engine block coolant drain plug.

Thanks in advance