File in Section:

Service Bulletin

Bulletin No.:
Date:

PI0689B
August, 2013

PRELIMINARY INFORMATION
Subject:

Aftermarket Installed Service, Tool or Utility Box Sagging, Mis-aligned, Forward Box
Mount Bracket Fractured on Trucks Equipped with Aftermarket Bodies

Models:

2011-2012 Chevrolet Silverado 2500HD-3500HD Series
2011-2012 GMC Sierra 2500HD-3500HD Series
Incomplete Vehicles Equipped with RPO ZW9 Box Delete and Aftermarket Bodies

This PI has been revised to remove the Warranty Parts Center (WPC) parts ordering form and
update the Parts Information. Please discard PI0689A.

Condition/Concern

2779514

Note: This PI involves incomplete vehicles that were manufactured without a factory installed cargo box assembly
that are equipped with an aftermarket Utility type body.

2779515

Example of mounting bracket with cracks developing (not all mounting points used).
Some customers may comment that the utility box is sagging, not level or misaligned. Upon inspection, the
technician may find cracked or fractured front bed mount bracket(s).
In rare occasions, situations have been identified where the incomplete pickup trucks have had an aftermarket body
(typically a service body or utility type body) installed. Upon inspection it was noted that the aftermarket bed was not
using all the recommended/available mounting points provided in Upfitter Integration UI Bulletin # 98 (available at
www.gmupfitter.com). Every case identified so far involved an aftermarket body that only used four mounting points;
one in each corner, with no additional load bearing points as described in the UI Bulletin.

2779516

Example of available body mounting locations not used by the upfitter under the service body.

2779517

Example of support bracket not carrying any load of the body.

Recommendation/Instructions
Warning: To avoid personal injury when exposed to welding flashes or to galvanized (Zinc Oxide) metal
toxic fumes while grinding/cutting on any type of metal or sheet molded compound, you must work in a
properly ventilated area, wearing an approved respirator, eye protection , earplugs, welding gloves, and
protective clothing.
Warning: Care should be used when handling the service part. Wear gloves to protect hands from sharp
edges.
As a result of the installation of the aftermarket box/bed not utilizing all the available attachment points, vehicles may
require the installation of replacement brackets to address or assist with customer concerns.
Important: If the existing body is going to be re-installed after the repair, then the mounting set up of the body that
contributed to this condition must be corrected to utilize the attachment scheme outlined in the UI Bulletin prior to
performing the re-installation of the body. This repair only replaces the same style of bracket, which requires the
correct mounting of the aftermarket body. If the body is not mounted properly, the condition may repeat. Refer to GM
Upfitter Bulletin #98' for 2011 & beyond `C/K HD Cab Chassis Mounting Guidelines' and “GM UI Body Builder’s
Manual Best Practices welding safety & procedures and body mounting information.”
Note: If the frame rail metal is damaged or torn, the frame rail (as an assembly) must be replaced (see GM collision
service procedures for replacement frames).
If the upfitter or customer decides to repair the existing frame condition without replacing the frame, GM does not
have an approved on-vehicle repair service operation. However, there are some collision repair “best practices” for
vehicle repair involving welding:
• Removal of the body is recommended to perform these operations. The body needs to be modified to correctly
mount to the chassis.
• When welding on the frame, all batteries must be completely disconnected from the vehicle.
• Care must be taken when welding around wiring, hoses, fuel tanks or any other components. All components
that can be damaged or present safety hazards must be protected and/or removed from the work area.
Use the following steps to replace the affected front bed mount brackets.
1. Disconnect all the negative battery cables. Refer to Battery Negative Cable Disconnection and Connection in SI.
2. Remove the box assembly. Identify the bracket(s) that need to be replaced.
3. Using a general purpose adhesive remover, remove any factory protective coatings and clean the area to be
repaired.
4. Remove or relocate any components in the repair area to allow full access to the repair and prevent damage to
vehicle components. Protect components from damage from grinding and welding procedures.
5. Scribe a line around the existing bracket to aid in aligning the replacement bracket.
6. Using a cut off wheel, cut the welds that attach the affected bracket to the frame.
7. Using a grinder, remove the remaining weld from the frame.
8. Prepare all attachment surfaces as necessary.

9. Apply GM–approved Weld-Thru Coating or equivalent to all mating surfaces. Refer to Anti-Corrosion Treatment
and Repair in SI.
10. Use the scribe marks to locate the bracket. Position the new bracket on the frame and clamp in place.
11. Weld the bracket to the frame.
12. Clean and prepare all of the welded surfaces.
13. Apply the required sealers and anti-corrosion materials to the repair area. Refer to Anti-Corrosion Treatment
and Repair in SI.
14. Reconnect all the negative battery cables. Refer to Battery Negative Cable Disconnection and Connection in SI.
Important: If the existing body is going to be re-installed after the repair, then the mounting set up of the body that
contributed to this condition must be corrected to utilize the attachment scheme outlined in the UI Bulletin prior to
performing the re-installation of the body. This repair only replaces the same style of bracket, which requires the
correct mounting of the aftermarket body. If the body is not mounted properly, the condition may repeat. Refer to GM
Upfitter Bulletin #98' for 2011 & beyond `C/K HD Cab Chassis Mounting Guidelines' and “GM UI Body Builder’s
Manual Best Practices welding safety & procedures and body mounting information.”
Note: The new bracket does not come with the attachment hole drilled. Install and align the box assembly and drill
the attachment hole in the bracket after the existing fasteners are installed.
15. Reinstall the box assembly.
16. Using an appropriately size drill, drill the mounting hole in the bracket.
17. Coat the hole with GM P/N 12371287 (in Canada, 10953437) SYNTHETIC LUBRICANT WITH TEFLON® to
prevent corrosion.
18. Install the mounting bolt.

Warranty Information
This repair is not covered under any GM Warranty provisions as a result of an aftermarket utility body not following
the installation guidelines described “GM Upfitter Bulletin #98' for 2011 & beyond.

Parts Information
Part Number

Description

23157861

LH REINFORCEMENT ASM-FRM #1 BOX MOUNT BRACKET

23157862

RH REINFORCEMENT ASM-FRM #1 BOX MOUNT BRACKET

12371287 (in Canada, 10953437)

SYNTHETIC LUBRICANT WITH TEFLON®