Ford 650 transmission question

Hello and thanks for taking the time to read this. I bought a Ford 650 last week that was "near perfect". Well the old caveat emptor bird got me again.
It had a little 'difficulty running' when we picked it up. The guy I bought it from knew less about tractors than I do. After a couple of days worth of head scratching and finally research, I got it running like a swiss watch. Note to non-mechanics...cylinders are numbered from the front to back! This bozo had put plugs and wires in the 650 and thought the cylinders were layed out from left to right as he read it, 4-3-1-2 doesn't work nearly as well as
1-2-4-3. That along with a new 12V battery installed should have had me drive the 175 miles back without the tractor. But, you know it is when that itch hits you.

So now that it starts and runs great, the shift linkage is my next problem. The transmission is strong in all gears, however it's anyone's guess as to what gear I'm in. The selector seems to change from movement to movement. One time reverse is at 'x' and the next time it's at 'y' or 'z'. Is there a slick way to check out the linkage without splitting the tractor?

Jim