Merchant Automotive Maximum Allison Transmission Pro Series DIY Kit, LB7 | 2003 - 2004

LB7 Pro Series Transmission Kit
Fits 2003–2004 GM LB7 Duramax with Allison 1000 5-Speed

Designed for serious power and built to take a beating, the Pro Series Transmission Kit is engineered for 2003–2004 LB7 Duramax trucks that have been modified with performance tuning, upgraded fuel systems, and increased horsepower.

This kit is the next step beyond a stock rebuild — it delivers the internal strength and shift control needed for high-output applications. Featuring GPZ high-performance frictions, precision steels, enhanced pressure plates, molded pistons, and reinforced clutch components, it’s built to hold serious torque while maintaining crisp, confident shifting under load.

Whether you're towing heavy, racing, or daily driving with extra horsepower, the Pro Series kit gives your Allison the durability and capacity to match.

Kit Highlights

Fits 2003–2004 LB7 Duramax with Allison 1000 5-speed

Ideal for trucks with performance tuning and fuel system upgrades

GPZ high-energy frictions and heavy-duty steels

Molded pistons and upgraded pressure plates for stronger, more consistent clutch apply

Pro-level internal components for long-term durability under elevated power

Merchant Automotive deep pan with filter lock

Comprehensive overhaul kit with upgraded shift calibration and valve body support

Kit Contents

Clutch Packs & Friction Materials

• GPZ187 C1 Friction, Internal Spline x8
• GPZ192 C1 Friction, External Spline x8
• GPZ175 C2 Friction x7
• GPZ196 C3/C4 Friction x12
• C5 High Energy Friction  x6
• C2 Steel x8
• C3/C4 Steel  x10
• C5 Steel  x6
• C1 Alto Apply Plate 
• C1 Alto Top Pressure Plate
• C3 Pressure Plate 
• C3/C4 Apply Plate  x2
• C3/C4 Molded Piston (LML/L5P style) x2
• Allison 1000 C3/C4 Piston Return Spring x2
• C1 Molded Clutch Balance Piston (5-Speed)
• C2 Molded Clutch Balance Piston (5-Speed)
• P1 Planet Shim

Transmission Internals

• Allison 5-Speed Overhaul Kit
• Allison T1 & T6 Bearing x2
• Allison T2 Bearing
• Allison 1000 T3–T5 Bearing x2
• Allison T4 Bearing
• Allison 1000 Front Pump Bushing
• Allison Stator Support Bushing
• Transfer Case to Transmission Adapter Gasket
• C1 Valve Kit – Quick Fill
• Pipe Thread Sealant Tape
• Allison Cut Back Valve
• Allison 1000 P1 Drive Flange

Upgrades & Components

• Allison 1000 Deep Pan Kit with Merchant Automotive Deep Filter Lock
• PTO Billet Side Cover, Pro Series x2
• Transmission Pro Clutch Kit
• Transmission Sub Kit – LB7 A Kit
• TransGo Allison Shift Kit (5-Speed)
• Valve Body Kit (400–800 HP rating)
• Allison Pressure Switch Assembly
• Transmission Pressure Regulator Spring Service Tool
• Trim Springs “A” & “B” x2
• F-Trim Sleeve
• Allison 1000 Pass-Through Connector Body & O-Ring

Tuned for power, built for battle — the Pro Series Transmission Kit gives your 2003–2004 LB7 the drivetrain strength and shift performance it needs to handle real horsepower. If you're serious about performance, this is the kit your Allison needs.