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Monster TH400
The legendary 3-speed heavy-duty transmission. Perfect for classic big-block or LS-powered 2500s where strength and simplicity are key.
Shop TH400
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Chevy Silverado 2500 Transmissions
From classic TH400 heavy-duty builds to modern Allison-equipped Duramax trucks, Monster Transmission offers Silverado 2500 solutions built for towing, hauling, and performance. Work, play, or performance—we’ve got you covered.
Engineered For Silverado 2500 HD Demands
Monster Transmissions are purpose-built for Chevy Silverado 2500 owners who need more than stock. With upgraded internals, improved clutch capacity, and dyno-tested confidence, our builds withstand the torque of big-blocks, LS swaps, and Duramax diesels.
From vintage TH400 swaps to modern Allison 1000 workhorses, we match the build and torque converter to your exact application.
Monster 4L80E
4-speed overdrive built to handle towing and big torque. Monster upgrades address direct clutches and planetary strength.
Shop 4L80EMonster 4L85E
Heavy-duty evolution of the 4L80E with higher torque capacity. Great for hauling, plowing, or performance builds.
Shop 4L85EMonster 6L90E
Modern 6-speed with added clutch capacity and gear spread for towing and drivability. Our builds solve 4-5-6 clutch and valve body issues.
Shop 6L90EMonster Allison 1000
The gold standard for Duramax-equipped Silverado HDs. Monster Allison builds deliver superior heat management and torque handling.
Shop Allison 1000Which Transmission Do I Have? — Silverado 2500 / 2500HD
Typical Silverado 2500/2500HD pairings by engine and model year. Edge cases exist—always verify by VIN or transmission tag.
| Transmission | Engine(s) | Typical Model Years | Notes |
|---|---|---|---|
| TH400 | Big-block gas (HD) | ~1973–1990 | 3-speed heavy-duty; common in pre-OD HD use |
| 4L80E | 5.7L / 7.4L gas; early HD | ~1991–1998 | Electronic 4-speed OD; HD workhorse of the ’90s |
| 4L85E | LS-based V8 (select HD) | ~1999–2007 | Higher-capacity 4L80E; 2007 Classic at end of run |
| 6L90E | 6.0L / 6.2L gas (HD) | ~2007–2021 | Modern 6-speed for gas HD; improved gear spread |
| Allison 1000 | 6.6L Duramax diesel | ~2001–2019 | Duramax-only factory pairing on 2500/3500 HD |
Why Silverado 2500 Owners Choose Monster
From dyno-tested builds to diesel-specific solutions, Monster ensures your 2500 is ready for work and play.
Heavy-Duty Components
Corrects GM weak points with billet shafts, stronger clutches, and calibrated hydraulics.
Matched Torque Converters
Spec’d to your power, gears, tires, and use case for lockup durability and heat control.
Dyno-Tested
Every 2500 transmission is live-tested to verify shift quality and performance before shipping.
Diesel & Gas Expertise
Solutions tailored for Duramax diesels and gas big-blocks alike.
Warranty Options
Baseline coverage with extended options for heavy commercial or towing applications.
Nationwide Shipping
Fast delivery on popular 2500 units with core return support.
Talk to an Expert
Need help choosing the right Silverado 2500 transmission?
Call 1-800-708-0087
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Silverado 2500 Transmission FAQ
Answers to common Silverado 2500 HD transmission questions.
Which transmission does my Silverado 2500 use?
It depends on year/engine. Older 2500s often ran TH400 or 4L80E. Heavy-duty models added 4L85E and later 6L90E. Duramax diesels typically came with the Allison 1000.
Do Monster builds fix the common 4L80E/6L90E problems?
Yes. Our builds address weak clutches, valve body issues, and heat management for towing and high-load use.
Is the Allison 1000 better than the 6L90E?
For Duramax diesels, yes—the Allison is purpose-built for high torque. For gas engines, the 6L90E is more common. Monster strengthens both for reliability.
Do your transmissions include a torque converter?
Yes. Every Silverado 2500 Monster build includes a converter matched to your engine, gearing, and usage.
How soon can I get my 2500 transmission?
Popular units like 4L80E, 6L90E, and Allison 1000 are often in stock. Call us for current ETAs based on build level.