If you study a parts BOOK, not sure it's mentioned in the parts look-up above, but even when the NF tractors were brand new and still being built, the inner rod that latches the lift lever into postion was NOT a servicable part. The whole lift lever and rockshaft had to be purchased as a complate welded assembly.
Think it was about 15 yrs ago I had one of the lift arms on the 72's rockshaft break off scraping ice off the driveway, too much side draft and too much "ramming speed". I took the whole rockshaft off and welded it back up, and in the process of moving the rockshaft on my work bench the top button hit something, not hard at all, but enough to break it. Then the inner rod twisted off. I had to make the new inner rod, bought the new top button, spring, washer, etc. assembled everything, last step was to heat & bend the lower end of the inner rod. You can not install it from below, has to be installed from the top while it's still straight, then bent. And you need a MAPP gas torch or acetylene torch to heat the bottom of the inner rod enough to bend properly.