Overview
The Crown Automotive J0947339 is a mainshaft gear for the M20 transfer case, with a gear designation of 18-8-49, 26 teeth and 10 spline. It is designed for use with a T14 transmission. It fits the 1972-1975 Jeep CJ5 (Base, Renegade) and the 1972-1975 Jeep CJ6 (Base).
Crown Automotive is a Jeep replacement parts maker, and this gear is offered as a replacement for the M20 transfer case in these early CJ models.
Key features
- Mainshaft gear for the M20 transfer case
- 26 teeth and 10 spline
- Gear designation 18-8-49
- Designed for use with a T14 transmission
- Replacement part from Crown Automotive
Gear wear and inspection
A mainshaft gear carries the full drive torque from the transmission into the transfer case, so its teeth and splines see constant load. Over time, wear shows up as rounded tooth faces, chipped edges, or a spline that feels loose when the gear is moved by hand. Gear whine, grinding in certain ranges, or a vehicle that jumps out of gear under load can all point to a worn internal gear, though other driveline faults can cause the same symptoms.
When a gear is replaced, check the parts that mesh with it, including the input gear and bearings, because a new gear running against a worn partner wears quickly. Clean the case thoroughly and confirm the gear turns smoothly before reassembly. Because this work involves the inside of the transfer case, keep the old parts for comparison and note how the shims and spacers were arranged.
- Inspect teeth for pitting, chipping or uneven wear
- Check spline fit against the shaft before installing
- Replace the mating gear or bearings if they show wear
- Confirm the transmission match before sourcing parts
Specifications
| Brand | Crown Automotive |
|---|---|
| Part number | J0947339 |
| UPC | 848399056426 |
| Transfer case | M20 |
| Teeth | 26 |
| Spline | 10 |
| Gear designation | 18-8-49 |
| Transmission match | T14 |
Vehicle fitment
The manufacturer fitment list covers the 1972-1975 Jeep CJ5 (Base, Renegade) and the 1972-1975 Jeep CJ6 (Base).
Models and years outside the CJ5 and CJ6 listing, including the CJ7, are not covered. Confirm your vehicle’s year, model and trim before ordering.
Installation notes
Because this is an internal transfer case gear, installation means working inside the case, so a qualified technician is the safer choice.