Zf M/T Synchro Ring 6SPD, 1ST & 2ND Blocker . Zf Manual Transmission 1st & 2nd Blocker Synchro Ring 6-speed Features and Benefits: ZF Manual Transmission 1st & 2nd Blocker Synchro Ring 6-speed Details: AAP UDA 4: 70 Grade Type: Regular Application Summary: 2001-2006 Chevrolet Silverado 2500 Hd (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 2001-2006 Chevrolet Silverado 3500 (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 2004-2006 Chevrolet C4500 Kodiak (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 2004-2006 Chevrolet C5500 Kodiak (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 2001-2006 GMC Sierra 2500 Hd (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 2001-2006 GMC Sierra 3500 (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 2004-2006 GMC C4500 Topkick (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 2004-2006 GMC C5500 Topkick (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 1999-2010 Ford F-250 Super Duty (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 2006 Ford F-350 (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 1999-2010 Ford F-350 Super Duty (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 1999-2010 Ford F-450 Super Duty (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual) 1999-2010 Ford F-550 Super Duty (1st and 2nd) (Transmission Base Gear: 6 & Transmission Control Type: Manual)