D8NN7N089AA torque converter seal.
Hopefully, you can just go in and replace the seal. BUT, it takes some doing to split and you shouldn’t just do a hurried job. At the very least, remove the torque converter, check flex plate for cracks. You may consider replacing the rear main seal and the rear freeze plugs as well at this time. Check the forward/reverse linkage roll pins for wear or looseness. Resealing the shuttle should be considered too, but if it shifts cleanly then you could avoid.
Up to you. It just takes time to split and buckle up.
On last tip, if you remove the steering box bolts on the bell housing after you loosen up the drag link, you can get the drag link all the way off the arm. The other method is taking the pitman arm off of the steering box, but if it has been on the shaft a long time…good luck with that.
Nice looking tractor btw. Side and front views would be nice!