Hopefully he is splitting the tractor, makes it easier to fix all the worn parts. That pin will have to be pressed out in a vice using spacers to push it partially out then you can drive it out the rest of the way with a punch
Splitting is easy.
Jack it up, just bearly off the ground.
Put some buckets under the footsy rest. Then remove all linkages and bolts.
Then roll it out using the jack.
Be sure you block the front wheels before you roll it out, heheh
When reinstalling, be sure the brake arm is is tied up so it will be above the rock shaft. BTDT
New solid pin installed, new roll pin also plus a better coupler and drive shaft.
After you flush out the gunk and put on the back plate. you can fill it by removing the plate on top of the tranny.