1000/M74 2004-2005 Chevy/GMC Silverado Sierra 2500HD 3500 8.1L AWD/4WD – Remanufactured 5-Speed Automatic Trans

Description

Configured for severe big-block 4WD service, Allison 1000 Remanufactured Automatic Transmission units for 2004-2005 GM 2500HD and 3500 8.1L four-wheel drive trucks controls harsh off-pavement hauling routes. This remanufactured unit handles 400 continuous input horsepower, 520 lb-ft maximum input torque, and 4800 RPM maximum input engine speed while maintaining mainline fluid pressure of 230 PSI.

A rigid die-cast aluminum casing encloses triple planetary gear modules fabricated from carburized 8620 steel. Segmented friction plates featuring spiral oil passages stop thermal breakdown across all internal clutch packs. Precision-machined valve body bores receive hard-anodized sleeves to stop hydraulic cross-leaks and shift shudder. Sump fluid volume holds 15.0 quarts of approved transmission fluid, feeding through 1/2-inch cooler ports. Total dry weight stands at 330 lbs, matched with a balanced lockup torque converter.

Key Features of Allison 1000

Fleet managers choose to buy Allison 1000 remanufactured automatic transmission units to eliminate slippage in four-wheel drive commercial service trucks. Rigorous remanufacturing replaces all friction components to guarantee stable hydraulic line pressure and uninterrupted torque transfer under maximum gross vehicle weight.

• 8620 alloy steel planetary gearsets absorb continuous 520 lb-ft big-block torque without tooth deflection.
• Segmented friction plates dissipate localized heat to prevent clutch burn during continuous uphill towing.
• 15.0-quart deep fluid pan prevents pump aeration on steep job-site grades.
• Sleeve-reinforced valve body prevents line pressure drop in this remanufactured Allison 1000 gearbox.
• 5 forward speeds span from a 3.10:1 launch gear through a 0.71:1 overdrive gear.
• 230 PSI mainline hydraulic pressure locks clutch packs fast to prevent intermediate slip.
• 29-spline output shaft interfaces straight with four-wheel drive transfer case hubs.

Hydraulic Line Pressure Thermal Dissipation

High-output internal fluid pumps maintain hydraulic mainline pressure between 190 and 230 PSI, keeping fluid sump temperatures within 165°F to 195°F. Input torque absorption handles 520 lb-ft at 3200 RPM without converter slip. The gear ratios progress from 3.10:1 in first gear to 0.71:1 in fifth gear overdrive, reducing big-block engine RPM at highway cruise speeds. Fluid cooler loops shed excess heat through 1/2-inch fittings, cooling rotating planetary gearsets and shielding thrust washers from thermal distress during continuous commercial hauling operations.

Transfer Case Output Shaft Interface

A 29-spline rear output shaft links straight with factory four-wheel drive transfer cases. Rear bearing retainer runout is held within 0.0015 inches on dial indicators to prevent transfer case vibration. Flange bolt patterns match factory adapter plates flush, maintaining precise driveline centerlines on commercial four-wheel drive chassis.

Computerized Dyno Screening Maintenance Procedures

Technicians subject every unit to hot-fluid dynamometer evaluation under simulated gross vehicle weight resistance to calibrate solenoid shift points, verify line pressure stability, and test lockup clutch grip. This transmission is not engineered for pro-mod drag racing, truck pulls, or vehicles running with clogged auxiliary transmission fluid coolers.

• Check transmission fluid dipstick level and color every 14 operating days.
• Replace synthetic transmission fluid and the spin-on filter every 25,000 miles.
• Flush transmission fluid cooler circuits every 12 months to clear internal sediment.

Commercial Crate Manifest Warranty Terms

A 3-Year unlimited mileage warranty covers fleet operators against mechanical and hydraulic defects nationwide. The heavy wood shipping crate holds the complete remanufactured automatic transmission, a balanced lockup torque converter, an external spin-on fluid filter, technical installation paperwork, and fluid specification documentation tags.