All of the Gravely sickle mowers I've owned had 3" sections with a 2" rivet spacing.
Yep, the only reason I used sections with 2 1/16" rivet spacing, is because I have a bunch of them. They were mainly used on Minneapolis Moline and Oliver.
Gravely also made a 2" sickle mower, and a model that looks like it had two knife bars, but no rock guards. But never saw those versions
Somebody on here had pics of the stubby rock guard version, earlier this spring.
Speaking of rock guards, I had promised some pics of replacing ledger plates on the original MD989 rock guards.
These are the tools needed. You can do this without the sickle anvil, I just happen to have one. The NOS IH ledgers were in the sealed can when I bought them. Also, IH ledgers use a special rivet with an odd angle on the countersink. Rivets and ledgers are still available from Case/IH.
Ledger tapped down and rivet going in.
Rock guard flipped and the rivet head being set on the post.
Rock guard on post and ready to be peened.
Completed rivet (these are countersunk, top and bottom).
I missed a pick of one right side up. I also did have to dress the top head of the rivet, just a little. Ready for a coat of paint.