The John Deere LA120 deck belt part number found is GY20570. The deck belt size found is 104 in (2,642 mm) long by 0.5 in (13 mm) wide. The drive belt part number found is GX20006. The drive belt size found is 89 in (2,261 mm) long by 0.5 in (13 mm) wide.
John Deere LA120 Belt Size and Part Numbers
| Mower deck belt part number | GY20570 |
|---|---|
| Mower deck belt length | 104 in (2,642 mm) |
| Mower deck belt width | 0.5 in (13 mm) |
| Drive belt part number | GX20006 |
| Drive belt length | 89 in (2,261 mm) |
| Drive belt width | 0.5 in (13 mm) |
Belt Size Comparison Chart
Belt length comparison
Belt width comparison
John Deere LA120 Belt Notes
| Mower deck belt note | The John Deere LA120 deck belt listing shows part number GY20570, length 104 in (2,642 mm) and width 0.5 in (13 mm). Use the listed value as a buying guide, not a blind substitute for the deck-specific parts diagram |
|---|---|
| Drive belt note | The John Deere LA120 drive or transmission belt listing shows part number GX20006, length 89 in (2,261 mm) and width 0.5 in (13 mm). This is separate from the mower deck belt |
| Fitment note | Belts are cheap until you buy the wrong one twice. On the John Deere LA120, confirm belt route, old belt label and OEM part number before ordering |
John Deere LA120 Belt Size FAQ
What should you watch when fitting a 104 in (2,642 mm) deck belt on the John Deere LA120?
A 104 in (2,642 mm) deck belt leaves little room for sloppy routing. This is a longer mower belt run, so twist, idler alignment and the belt keeper positions matter. A belt can be the right length and still fail if it is routed wrong. Before blaming the new belt, compare the belt path to the routing decal and make sure it sits on the correct side of each.
Can you replace the John Deere LA120 belt with the same length but different width?
The deck belt width found is 0.5 in (13 mm). That is the common 1/2-inch belt width range. Still match the OEM number because the belt angle, fabric wrap and effective length can differ. A belt with the wrong top width can ride too high or too low in the pulley even if the length looks right
Why are there separate belt part numbers for the John Deere LA120?
The captured values separate the belt jobs: deck belt part number GY20570 and drive belt part number GX20006. Treat each number as position-specific and confirm it against the parts diagram before ordering
Mistakes do happen. Belt specs can change by year, mower deck, pulley layout, serial range and regional parts catalog. Please check the operator manual, belt routing decal, old belt label and official John Deere parts catalog before ordering a replacement belt.
