You're comparing diesel transmissions. The Allison 1000 (Duramax) vs 68RFE (Cummins) debate is one of the oldest in the diesel world. Here's the real comparison.
Quick stats
Allison 1000:
- Behind Duramax (2001+)
- 5-speed (early) or 6-speed (2006+)
- ~765-910 ft-lb stock capacity
- Industry leader for HD use
- Premium fluid (Transynd)
68RFE:
- Behind 6.7L Cummins (2007.5+)
- 6-speed
- ~610 ft-lb stock capacity
- Designed by Chrysler/Mopar
- ATF+4 fluid
Strength comparison
Stock-power:
- Allison 1000: Excellent — overbuilt for stock Duramax
- 68RFE: Adequate — fine for stock Cummins
Mild tune (mild Duramax/Cummins):
- Allison 1000: Excellent — handles mild tune well
- 68RFE: Needs HD parts (billet input, HD direct clutch)
Tuned/race:
- Allison 1000: Still very strong, race-proven
- 68RFE: Requires complete HD build to keep up
The verdict on strength:
Allison 1000 wins for HD use. 68RFE adequate but needs more help to handle power.
Cost comparison
Stock rebuild:
- Allison 1000: $4,000-5,500
- 68RFE: $4,000-6,500
Tuned rebuild:
- Allison 1000: $5,500-9,000
- 68RFE: $6,000-12,000
Race rebuild:
- Allison 1000: $8,000-15,000
- 68RFE: $10,000-18,000
Allison generally cheaper per HP capacity.
Fluid
Allison Transynd:
- Premium synthetic
- $15-25/quart
- 16+ quart capacity = $250-400+ per fluid change
- Service every 50K (normal) or 25K (severe)
ATF+4 (68RFE):
- $8-14/quart
- 14-15 quart capacity = $120-200 per fluid change
- Service every 50K (normal) or 30K (severe)
Allison costs more to maintain.
Aftermarket support
Allison 1000:
- Massive aftermarket
- Multiple specialty builders (ATS, Suncoast, Goerend, Inglewood)
- Race-proven for sled pull and drag
68RFE:
- Growing aftermarket
- Specialty builders (ATS, BD, Goerend)
- Less race history than Allison
Allison wins for aftermarket support.
What this means for ownership
Duramax owner with Allison 1000:
- You have the better trans
- Cheaper to operate per power level
- Read our best Allison 1000 rebuild kit guide
Cummins owner with 68RFE:
- Good trans, manage expectations
- HD parts mandatory for any serious tune
- Read our best 68RFE rebuild kit guide
The verdict
For raw strength: Allison 1000
For aftermarket support: Allison 1000
For maintenance cost: 68RFE
For initial cost: Tied
If you're starting fresh: pick the engine first. Allison comes with Duramax, 68RFE with Cummins. You're not really choosing between them in a swap.
If you're choosing between the trucks: this is just one of many factors.
Need Allison or 68RFE parts? Shop our Allison catalog or 68RFE catalog. HD master kits, billet input shafts, performance torque converters. Free shipping over $70.
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