88-98 Chevy GMC OBS & C1500 Bolt-In Rear Frame C-Notch Kit

88-98 Frame C-Notch Kit - #135-4005

Modernize your 1988-1998 Chevy & GMC C1500 (OBS) with the most robust bolt-on C-notch kit on the market. Engineered with the builder in mind, this kit provides the necessary axle clearance for lowered stances while significantly reinforcing the factory frame rails. Precision-manufactured for the GMT400 platform, this kit ensures a professional-grade foundation for trucks lowered more than 4 inches, preventing harsh axle-to-frame contact without the need for a welder.

The GSI Advantage

• 100% Bolt-In Solution: Designed for ease of installation, this kit eliminates the need for extensive fabrication. It’s a straightforward process that can be completed with basic shop tools, making it the ideal choice for a one-person install.

• Maximum Reinforcement: Measuring an impressive 25-1/2" in length, our notches distribute stress loads across a much larger surface area than standard kits. This added length significantly increases frame rigidity and strength.

• Premium Corrosion Resistance: To guarantee long-term durability and a show-quality look, every notch comes finished in a semi-gloss black powder coat.

• Precision Metal Template: We include a heavy-duty metal installation template to ensure perfect alignment and cutting. This removes the guesswork, ensuring your notches are positioned exactly where they need to be for maximum travel.

Design & Construction

• Weight: 42 lbs (Total Kit) / 21 lbs (Per Notch)

• Dimensions: 25.5" x 3.5" x 5.25" (Per Notch)

• High-Strength Steel: Laser-cut and formed for a precision fit over GMT400 frame rails.

• Overbuilt Hardware: Includes (32) 1/2"-13 Grade-8 hex bolts for a secure, permanent, and vibration-free fit.

• Finish: Mil-spec semi-gloss black powder coat.

Measurement & Fitment Guide

This kit is engineered specifically for the 88-98 C1500 (GMT400) frame. Proper fitment is critical for maintaining suspension geometry and safety.

When to use this kit:

• Rear Drops: Required for rear drops of 4" or greater to maintain proper suspension travel.

• OBS Builders: Specifically contoured for the 1988-1998 Chevy/GMC C1500 frame rails.

• High-Performance Use: The 25-1/2" extended design makes this ideal for high-horsepower or heavy-use street trucks that require extra frame support.

Vehicle Applications

• 1988-1998 Chevy C1500 (2WD)

• 1988-1998 GMC C1500 (2WD)

• Fits "OBS" / GMT400 Platform Regular Cab, Extended Cab, and Crew Cab models.

What’s Included

• (2) Driver & Passenger Side C-Notches (25-1/2" Long)

• (1) Precision Metal Template

• (32) 1/2-13 Grade-8 Hex Bolts

• (32) 1/2-13 Grade-8 Lock Nuts

• (64) Grade-8 Flat Washers

Questions? Contact Us

(480) 940 1806 – Local
1 (877) 951-1890 – Toll Free

At GSI Machine & Fabrication, we offer a one-year warranty on all manufactured parts, covering defects upon inspection. However, we are not liable for personal or property damages resulting from misuse of our products. Note that warranties for non-manufactured parts, such as shocks or ball joints, must be handled directly with the part’s manufacturer.

Orders may be canceled before shipment, except for special-order and custom items, such as chassis products and air ride suspension. Refunds for eligible returned items will exclude shipping costs and may incur additional fees. For cancellations or issues with orders, contact our customer support at 1 (877) 951-1890 or sales@gsimfab.com.

Customers are responsible for all customs fees, duties, and taxes on international orders. Once your package is shipped, we are not liable for damage, theft, or loss during transit. Please inspect your delivery promptly and report any issues within 48 hours. For international shipments, local policies may cause delays, and additional documentation may be required. Always ensure shipping details are accurate to avoid additional costs.