You're trying to figure out which transmission is in your GM truck. The 4L60E and 6L80 are both common but very different. Here's how to identify yours and what it means for ownership.
Quick identification
By year and application:
4L60E (1993-2014+ depending on application):
- 1500-series Silverado, Sierra (1999-2014)
- Tahoe, Yukon (1995-2014)
- Suburban 1500 (1995-2014)
- Most small-block V8 applications
- 4-speed automatic
6L80 (2007+):
- Silverado 1500, Sierra 1500 (2007+)
- Tahoe, Yukon (2007+)
- 6-speed automatic
If your truck is 2007 or newer, it's almost certainly a 6L80 (unless it's an older holdover model).
If your truck is 2006 or older, it's a 4L60E.
By VIN or RPO code
RPO sticker (typically in glove box):
- M30 = 4L60E
- M70 = 4L70E
- M82 = 6L80
- M5T = 6L80E
By trans pan
- 4L60E: roughly 16-bolt pan
- 6L80: different pan shape, fewer bolts (about 13)
By shift count
- 4L60E shifts at: about 1-2, 2-3, 3-4 (4 forward gears)
- 6L80 shifts at: many more shift points (6 forward gears)
Key differences
Gear count
- 4L60E: 4 forward gears
- 6L80: 6 forward gears (better fuel economy, smoother)
Torque capacity
- 4L60E: ~340 ft-lb stock
- 6L80: ~480 ft-lb stock
Internal complexity
- 4L60E: Simpler, more aftermarket support
- 6L80: More complex electronics, more solenoids
Rebuild cost
- 4L60E: $1,500-3,500 typical
- 6L80: $2,500-4,500 typical
Common failures
- 4L60E: Sun shell, TCC apply piston, 2-4 band
- 6L80: Wave plate, TCC shudder, solenoid pack
Parts availability
- 4L60E: Excellent, mature aftermarket
- 6L80: Good, growing aftermarket
What this means for ownership
If you have a 4L60E:
- Cheaper to rebuild
- Wide parts availability
- Worth investing in HD upgrades during rebuild
- Read our best 4L60E rebuild kit guide
If you have a 6L80:
- More complex but more refined
- Watch for the famous TCC shudder
- Read our 6L80 shudder fix guide
- Read our best 6L80 rebuild kit guide
Which is "better"?
4L60E advantages:
- Simpler to rebuild
- Cheaper parts
- Wide aftermarket
- Easier swap candidate
6L80 advantages:
- 6 forward gears (better fuel economy)
- Higher torque capacity
- More refined
- Newer design
For a daily driver: whichever your truck has is fine.
For a swap: depends on your goals. 4L60E for budget, 6L80 for modern feel.
For HD use: 4L80E or 6L80, not 4L60E.
Need parts for your trans? Shop our 4L60E catalog or 6L80 catalog. Master kits, Sonnax HD parts, complete rebuild solutions. Free shipping over $70.
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