Shimming the axles on a 9n / 8N comes up often here , you can buy paper gaskets and keep adding . I also have a 3000 which the process is the same , but when looking for shims all if find is a $40 shim and I don't think I have seen any paper gaskets .
The shims are 9 hole and the same as the 601 , 641 , 801 , 841 , and the diesel 3 cylinder thousand series . I have purchased many used and new old stock over the years and do not think I will need any more . Just thought I would post this link for anyone that wants to prepare for an upcoming axle shim project . These used sets come up every few months on ebay .
I made a rough shim out of aluminum flashing and did not like the process :( so I decided to stock up :) https://www.ebay.com/itm/Ford-Tractor-601-641-801-841-861-Rear-Axle-Shims-6/153942286427?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649