Generally when these transmissions pop out of 3rd it is because of wear in the syncro. Also, the small spring ring on the clutch gear could have some wear. Check for bad u-joints and/or driveshaft carrier bearing that can cause a vibration that will also cause it to fall out of gear.


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine