Second gear is on the mainshaft and has the center bearing right behind it. There are 3 bearing in an OD transmission and likely all of them are bad. Other components are worn out as well as no amount of clunking is a good sign.
Some components such as cluster gears and syncros for those transmissions are in very short supply.
Fred


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