BST BSSP 12.5" Extended Square U-Bolts Kit for 2.5" Leaf Springs, 9/16" Bolts — Complete Hardware, Heavy-Duty

BST BSSP 12.5" extended square U-bolts kit secures 2.5" wide leaf springs with 9/16" bolts on 1988–2019 Chevy Silverado/GMC Sierra 1500 trucks.

This heavy-duty hardware set replaces or upgrades the U-bolts that clamp extended leaf springs to the axle on many full-size Chevy and GMC half-ton trucks. The kit includes four 12.5" long square U-bolts sized for 2.5" spring packs using 9/16" bolts, plus matching mounting hardware. It’s intended for applications where you’ve added or swapped rear blocks, fabricated extra leaf springs, or need longer U-bolts to accommodate lifted or modified rear suspension assemblies.

How do these U-bolts fit my 1988–2019 Chevy Silverado or GMC Sierra 1500?

The BST BSSP U-bolts are engineered for leaf springs that are 2.5" wide and require a 12.5" inside-bend length with 9/16" bolts. They are suitable for many stock and modified rear spring setups across model years listed. Verify spring pack width and required bolt diameter before ordering to ensure correct fitment.

• Designed for 2.5" wide leaf springs and 9/16" bolt holes
• 12.5" measured from inside of the bend to match common extended spring needs
• Compatible with 1988–2019 Silverado 1500, Sierra 1500, and C1500 rear suspensions
• Includes hardware for straightforward replacement of worn or undersized U-bolts

What does the kit include and how is the hardware packaged?

The package contains a set of four square U-bolts plus the necessary mounting hardware for installation. The parts are grouped so you get both driver- and passenger-side U-bolts and matching nuts and plates. This makes it easy to replace all rear U-bolts at once, ensuring even clamping and reliable alignment of the axle to the springs.

• Four 12.5" long square U-bolts sized for 2.5" springs
• Included mounting plates and nuts for each bolt
• Packaged as a complete set for left and right sides, front and rear placement
• Ready for direct swap or use with lifted/repaired spring assemblies

Why choose square U-bolts for leaf spring applications?

Square U-bolts distribute clamping force over the spring perch and axle tube more evenly than round variants in many setups, reducing localized stress and helping keep spring packs aligned. For trucks with extended or added leafs, square U-bolts offer a reliable clamping footprint that resists shifting under load or during off-road driving.

• Better contact on flat spring perches for improved clamp stability
• Reduced spring pack rotation and movement under load
• Durable construction suited for towing, hauling, and lifted applications
• Ideal when rear blocks or extra leaf springs increase stack height

How should I inspect and install these U-bolts safely?

Always replace U-bolts in matching sets and torque hardware to factory or axle-maker specifications. Inspect spring packs, perches, and axle tube for wear or deformation before installing new U-bolts. Use a calibrated torque wrench and recheck torque after the truck has been driven and re-settled under load.

• Replace all rear U-bolts at once for balanced clamping
• Torque nuts to manufacturer specifications and retorque after initial use
• Check spring perches and axle tube for cracks, wear, or corrosion first
• Use thread lubricant or anti-seize if recommended for your application

Who is this for: This BST BSSP U-bolt kit is suited to DIY truck owners, mechanics, and fabricators working on 1988–2019 Chevy Silverado and GMC Sierra 1500 series vehicles who need longer U-bolts for extended or modified leaf spring setups. It’s useful when reassembling suspension after installing rear blocks, adding extra leafs, performing lift conversions, or replacing worn hardware to restore secure axle-to-spring clamping.