Allison makes both the 1000 series (Duramax pickup) and 2000 series (commercial). They look similar but they're different transmissions. Here's how to tell which is yours.
Quick spec comparison
Allison 1000:
- ~900 ft-lb capacity
- 5-speed (early) / 6-speed (late)
- GM Duramax 6.6L applications
- Pickup truck use
Allison 2000 series:
- ~1,000-1,200 ft-lb capacity
- 5-speed standard
- Commercial truck use
- Higher GVWR applications
How to identify
Allison 1000 indicators:
- Found in GMC/Chevy 2500HD/3500HD pickups
- 2001-present
- 6.6L Duramax behind it
- Pickup truck application
Allison 2000 indicators:
- Commercial truck
- Often medium-duty (Ford F-650, Chevy Topkick, Freightliner)
- Different engine combinations
- Higher GVWR rating
Read our identify your transmission
Strength comparison
Allison 1000:
- Stock: ~900 ft-lb
- With HD: 1,200+ ft-lb
- Read our best Allison 1000 rebuild kit
Allison 2000:
- Stock: ~1,000-1,200 ft-lb
- With HD: 1,400+ ft-lb
- Heavier internals
Parts interchange
Mostly NOT interchangeable:
- Different case
- Different internals (sized for different loads)
- Different mechatronics
- Don't try to swap parts blind
Some external parts shared:
- Some sensors
- Some external lines (verify)
Common failures
Allison 1000:
- Mechatronics solenoids
- Read our Allison 1000 mechatronics
- TCC apply
- Read our Allison 1000 TCC apply
- C2 clutch under HD use
Allison 2000:
- Internal clutch wear (HD use)
- Pump wear at high miles
- Solenoid pack wear
Rebuild costs
Allison 1000:
- DIY: $2,500-$4,000
- Shop: $4,500-$7,000
Allison 2000:
- DIY: $3,000-$5,000
- Shop: $5,500-$9,000
More expensive — larger parts
Service intervals
Both:
- Allison Transynd fluid only
- 30,000-50,000 mile pan service
- Read our how to flush transmission fluid
When to choose which (engine swap)
Generally these stay in their factory trucks
- Bellhousing patterns specific
- Wiring/ECM integration complex
- Better: rebuild what's in the truck
For project builds:
- Most rebuilders specialize in Allison 1000
- 2000 series often goes back to OEM-pattern truck
Read our diesel tow rig setup
Aftermarket support
Allison 1000:
- Mature aftermarket
- Sonnax, ATS, SunCoast, BTS
- Read our Sonnax explained
Allison 2000:
- Less aftermarket
- More OEM-focused
- Specialty commercial rebuilders
Diagnostic tools
Both work with:
- Allison DOC (most comprehensive)
- Edge bidirectional
- Read our Allison P0700
Operating practices
Both benefit from:
- Aux cooler (large)
- Trans temp monitoring
- Premium fluid (Transynd)
- Read our transmission temperature monitoring
Avoid:
- Aggressive tunes
- Skipped service
- Cheap fluid substitutes
Need Allison 1000 or 2000 parts? Shop our Allison catalog. Rebuild kits, solenoids, HD upgrades. Free shipping over $70.
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