Chevrolet Silverado / GMC Sierra. Service manual - part 1274

Fig. 19: View Of 50 mm Backing Plate 
Courtesy of GENERAL MOTORS CORP. 

2. Create a 50 mm (2 in) backing plate from the unused portion of the service part. Trim the backing plate as 

necessary to fit behind the sectioning joint. 

 

2008 Chevrolet Silverado 1500 

2008 ACCESSORIES & EQUIPMENT Collision Repair - - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & 

Silverado

  

Fig. 20: Drilling 8 mm Plug Weld Holes 
Courtesy of GENERAL MOTORS CORP. 

3. Drill 8 mm (5/16 in) plug weld holes along the sectioning cut on the remaining original part. Locate these 

holes approximately 25 mm (1 in) (a) from the edge and spaced 40 mm (1 1/2 in) apart. 

 

2008 Chevrolet Silverado 1500 

2008 ACCESSORIES & EQUIPMENT Collision Repair - - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & 

Silverado

  

Fig. 21: Drilling Windshield Frame Pillar Plug Weld Holes 
Courtesy of GENERAL MOTORS CORP. 

4. Drill 8 mm (5/16 in) plug weld holes in the service part as necessary in the locations noted from the 

original panel and along the sectioning cut. 

IMPORTANT: If the location of the original plug weld holes can not be determined, or if 

structural weld-thru adhesive was present, space the plug weld holes 
every 40 mm (1 1/2 in) apart.

 

2008 Chevrolet Silverado 1500 

2008 ACCESSORIES & EQUIPMENT Collision Repair - - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & 

Silverado

  

Fig. 22: Plug Welding Backing Plate 
Courtesy of GENERAL MOTORS CORP. 

5. Prepare all attachment surfaces as necessary.  

6. Apply GM-approved Weld-Thru Coating or equivalent to all mating surfaces. Refer to Anti-Corrosion 

Treatment and Repair .  

7. Fit the backing plate (2) halfway into the sectioning joint, clamp and plug weld to the vehicle (3). 

 

2008 Chevrolet Silverado 1500 

2008 ACCESSORIES & EQUIPMENT Collision Repair - - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & 

Silverado