Knowing how inventive past Gravely owners can be, it could have been anything. What comes to my mind.....
a. beverage holder, you could even use a piece of tubeing for a straw if you had too.
b. a can of Bee spray (when you need one, you need it fast).
c. can of penetrating oil (just because you never know when you'll need it)
d. a place to hold the rope starter.
e. a quart bottle of gas (incase you run out while working the back 40)
f. Thermos holder. I hate cold coffee.
g. storage for the split hitch when not in use.
h. nails and pliers (incase there is a whole in the fence on the back 40)
i. when you are done plowing you fill it with worms for bait.
j. maybe the old owner had a peg leg like a pirate and he stuck it in the pipe!
k now-a-days somebody would probably put a bottle of PUREL in it!
My sulkie came with a home made tool box mounted to the axle about 8 inches square and the length of the axle. always seemed like alot of work to go thru unless you thought it was going to be really useful. But the inside looks like it's never had anything in it!
You did a beautiful job on the restoration, enjoy it and thanks for posting it.
ED