TC Remanufacturing HD1221 Automatic Transmission Torque Converter

Automatic Transmission Torque Converter for HD Trucks

TC Remanufacturing HD1221 is an automatic transmission torque converter built for heavy-duty Chevrolet, GMC, and Hummer applications. It features a 13.50-inch converter diameter, a 1700-1900 stall range, and a billet cover for added strength in demanding drivetrain service.

Compatible With 2001-2019 Chevrolet Silverado 2500 HD, 2007-2019 Chevrolet Silverado 3500 HD, 2001-2014 GMC Sierra 2500 HD, 2007-2014 GMC Sierra 3500 HD, and 2006 Hummer H1 applications. Part number HD1221 is also identified by converter codes 221, 29530317, 29530319, 29538347, 29538528, 29540484, 29543017, and 29549519.

Key Features

• Billet cover construction for added durability
• 13.50-inch converter diameter
• 1700-1900 stall speed range
• 11.50-inch bolt circle
• 6-hole threaded mounting type
• 10mm x 1.5 mounting thread size
• 25-spline hub with milled flats
• 1.703-inch pilot diameter
• Black sticker visible marker

Detailed Description

TC Remanufacturing HD1221 is an automatic transmission torque converter for Chevrolet Silverado 2500 HD, Chevrolet Silverado 3500 HD, GMC Sierra 2500 HD, GMC Sierra 3500 HD, and Hummer H1 fitments listed above. The billet cover and threaded 6-hole mounting design support heavy-duty transmission service, while the 1700-1900 stall range helps match drivability and launch characteristics for the listed applications. If you are replacing a worn torque converter in a Silverado 2500 HD, Silverado 3500 HD, or Sierra HD truck, HD1221 provides the core dimensions and mounting specs needed for a direct application match.

This part number, HD1221, cross-references converter codes 221 and 29530317 for the same application.

Common Problems This Part Can Address

• Shudder or vibration from a worn torque converter
• Delayed engagement during acceleration or takeoff
• Excessive slip under load
• Noise or rough operation from internal converter wear
• Fitment issues when replacing a converter with the wrong bolt circle, spline count, or pilot size

Installation Notes and Tips

Verify the converter diameter, 25-spline hub, 1.703-inch pilot diameter, 11.50-inch bolt circle, and 10mm x 1.5 threaded mounting pattern before installation. Confirm the transmission and engine combination against the vehicle listing for your Chevrolet Silverado 2500 HD, Chevrolet Silverado 3500 HD, GMC Sierra 2500 HD, GMC Sierra 3500 HD, or Hummer H1 application. Always inspect the transmission fluid, cooler, and flexplate condition during replacement to help prevent repeat failure.

Quality Assurance

TC Remanufacturing supplies remanufactured drivetrain components for service replacement applications. HD1221 is built around the listed OE-style dimensions and converter codes to support accurate fitment in the specified heavy-duty truck applications.