Description

Peterbilt 330, 325, 337, 348 Technical Manual – Body Builder Edition

If you’re building a dump bed, utility box, or any custom body onto a Peterbilt medium-duty chassis, you need the factory specs. I’ve seen too many guys drill frame rails in the wrong spot because they used a generic diagram from some forum. That gets expensive fast. The Peterbilt 330, 325, 337, 348 Technical Manual is the only document Peterbilt themselves hand to body builders. It’s 76 pages of dimensional data, frame drilling limits, electrical junction box pinouts, and hybrid system connections. Nothing generic.

Here’s the reality: every chassis is certified incomplete. That means you, the body builder, are responsible for making sure the final vehicle meets FMVSS and CMVSS. This manual spells out exactly what’s required in Section 2 – Safety and Compliance, including noise and emissions. You’ll find the incomplete vehicle certification process on page 1-1. Don’t skip that section unless you want liability headaches later.

Peterbilt 330, 325, 337, 348 Technical Manual: Dimensions and Turning Radius

Section 3 runs through overall dimensions for all four models. Single rear axle, tandem axle, standard cab, crew cab – they’re all drawn out. You get turning radius data on page 3-1, plus side views that show exact cab and hood lengths. Need to know battery box step height for the 325? It’s there. Fuel tank location for the 340 (now 348)? Also there. Every dimension is in inches and pounds – imperial all the way, no metric conversions that get rounded wrong.

The manual covers exhaust locations for DPF setups with horizontal diffusers, vertical stacks, and under-cab configurations. If you’re routing a body over the exhaust, you need those clearances. I’ve seen melted wiring harnesses because someone assumed a stack was six inches further out than it actually was. Don’t be that guy.

Body Mounting Using Brackets or U-Bolts

Section 4 breaks down the two approved mounting methods. Brackets require specific frame sill spacers and mounting hole patterns. U-bolts need spacers between the frame and body rail. The critical clearance section warns about rear wheel contact with the cab during articulation. If you’re putting a service body on a 330, read that part twice. The table on frame drillings shows maximum hole diameter and edge distance – those numbers are tighter than most aftermarket guides admit.

Related manual you might need: Peterbilt 330 Operators Manual – Factory Specs & Safety” target=”_blank”>Peterbilt 330 Operators Manual – Factory Specs & Safety for daily operation procedures.

Frame Modifications: Drilling Rails and Welding Precautions

Section 5 is where most mistakes happen. The manual explicitly forbids welding on frame rails unless you use an approved procedure. It gives the exact hole pattern locations – not a vague “drill in the neutral zone.” It also covers frame inserts for lengthening the wheelbase and how to reposition crossmembers. Page 3-1? That’s turning radius, but for frame drilling specs you’ll be in Section 5. Pay attention to the “Location and Hole Pattern” subsection. That data comes straight from Peterbilt engineering, not some third-party guess.

Electrical System: Body Lights Junction Box and Remote PTO

Section 6 details the body lights junction box (BLJB) and its connector pinouts. If you’re adding strobes, backup alarms, or work lights, you tap into that box using Peterbilt’s designated circuits. The remote PTO harness is documented with wire colors and current ratings. There’s also a subsection for third battery installation – critical if your body draws heavy amps while idling. Run a separate ground wire; the manual shows where to bolt it.

Hybrid Utility Application for Models 330 and 335

Section 7 is specific to the hybrid models (330 and 335). It covers the Power Electric Carrier (PEC) placement and the EPTO (electric PTO) functionality. Body builders can connect to the hybrid system for auxiliary power. The manual includes sections of the MD Hybrid Electrical Schematics on Body Builder Connections. If you’re fitting a hybrid chassis with a refuse body or a utility bucket, you need those diagrams. Don’t rely on a photocopy from a Facebook group.

For further reading on transmissions: Manual Transmission” target=”_blank”>Manual Transmission and Manual Transmission” target=”_blank”>Manual Transmission – but remember, this manual covers body building, not drivetrain overhaul.

Vehicle Identification: VIN Location and Certification Labels

Appendix A tells you where to find the VIN and chassis number on each model. It also reproduces every certification label: tire and rim data, incomplete vehicle certification, noise emission, paint ID. If you’re rebodying a used chassis, you’ll need those label specs for compliance. The manual even lists engine, transmission, front and rear axle identification – so you can verify what you’re actually working with.

Routing Requirements for Wiring and Hoses

Appendix C is a nightmare to ignore. It defines routing for wiring bundles, air compressor discharge hoses, and exhaust system clearance. Exceptions are allowed only if you follow specific spacing rules. The manual gives minimum distances between wiring and moving components. I’ve seen air lines chafe through because they were zip-tied to a sharp frame bracket. This appendix would have prevented that.

Need weight distribution data? Appendix B lays out the body builder’s responsibility for axle loading. A table shows front and rear axle capacities for each model. You calculate the center of gravity of your body and make sure it doesn’t exceed the frame rail rating. No guesswork.

FAQ

Does this manual cover engine torque specs?

No. This is a body builder manual, not a service manual. It covers frame dimensions, electrical connections, hybrid systems, and safety compliance. For engine and transmission specs, you need the separate service manual.

Are the dimensions in inches or centimeters?

Inches and pounds throughout.

Can I weld on the frame rails?

The manual permits welding only if you follow the specific precautionary procedures in Section 5. It lists acceptable weld types and locations. Unauthorized welding can weaken the heat-treated rails. If you’re not sure, use the drilling and bracket methods instead.

What’s the difference between the 337 and the 348?

The 348 is the tandem-rear-axle version of the 337. Dimensions for each are shown separately in Section 3. The hybrid section applies only to 330 and 335 models.

Get the full document and stop working from photocopies. Peterbilt 210, 220 Technical Manual – Factory Shop Specs” target=”_blank”>Peterbilt 210, 220 Technical Manual – Factory Shop Specs and Peterbilt FLEX Air Suspension Service Manual” target=”_blank”>Peterbilt FLEX Air Suspension Service Manual are also available if you need those systems. But for your body build, start here. Access the Factory Manual and keep a copy on your shop tablet – you’ll reference it every time you drill a hole.