The SPOOLOGIC Turbine Shaft 10 Blade SL-240-021 is an OEM-spec replacement turbine shaft for the GT3788VA turbocharger on 6.6L LLY Duramax applications. Built to factory geometry — same 10-blade Inconel superalloy turbine wheel, same shaft length, same compressor-end thread — so the new shaft drops into the bearing housing and accepts the original compressor wheel and lock nut without modification. This is a direct OEM-spec replacement only — no performance changes to blade count, trim, or geometry.

OEM-Spec Replacement, Not a Performance Upgrade

This shaft is a service-replacement part built to the original turbo's specifications. Same blade count, same wheel trim, same shaft dimensions, same material grade as the part it replaces. It is the correct choice when a turbine shaft is bent, scored on the seal land, or the wheel is damaged from a foreign object event and the rest of the CHRA is still serviceable. It is not a performance-trim wheel and will not change spool, flow, or top-end power compared to a healthy stock shaft.

Inconel Superalloy Turbine Wheel

The turbine wheel is forged from Inconel — a nickel-chromium superalloy that holds its strength at the exhaust gas temperatures the wheel sees in service. The shaft is alloy steel, friction-welded to the wheel for a single-piece assembly with no joint to fatigue. Compressor-end threads are machined to OEM spec so the original compressor wheel and lock nut torque correctly during reassembly.

Features

• OEM-spec 10-blade turbine wheel — same blade count, trim, and exducer diameter as the factory shaft it replaces
• Inconel nickel-chromium superalloy turbine wheel — holds strength at sustained EGT
• One-piece friction-welded shaft and turbine wheel assembly — no joint to fatigue between shaft and hub
• Machined compressor-end threads to factory torque spec — accepts the original compressor wheel and lock nut
• Shaft journal and seal lands machined to OEM dimensions for clean bearing housing fit
• Service-replacement part — built for rebuilders restoring a damaged or worn factory shaft to original spec

What's Included

• Turbine shaft and wheel assembly — 1

Installation Notes

Every new turbine shaft must be VSR (Vibration Sorting Rig) balanced as a complete rotating assembly with the compressor wheel and lock nut installed. Skipping post-install balancing on a CHRA balancer is the most common cause of premature bearing failure. The compressor wheel must be torqued to OEM spec with a calibrated torque wrench, and shaft endplay and bearing clearance must be verified against factory service data before the turbo is reassembled.

Fits 2004.5-2005 6.6L Duramax LLY

• 2004.5 – 2005 Chevrolet Silverado GMC Sierra 2500 / 3500 6.6L Duramax LLY

Replaces Factory OEM Part Numbers

• 736554-0015, 740659-0010, 759622-0005, 97387896, 98011735

DIY Product — All Sales Final, No Warranty, No Returns

This SPOOLOGIC turbine shaft is a professional DIY assembly product intended for experienced turbo builders and rebuild shops. Successful installation requires proper tools, OEM service procedures, cleanliness standards, correct wheel-to-shaft fitment, and high-speed VSR balancing of the completed rotating assembly before return to service. Because SPOOLOGIC has no control over installation quality, balancing accuracy, or the condition of the parts the shaft is installed into, all sales are final — no warranty, no returns, no exchanges. By purchasing this shaft you acknowledge that you are responsible for correct installation, balancing, and verification.