TSC usually has 'em. AGCO/Massey Ferguson will have 'em. Valu-bilt's got 'em. Agri-supply carries 'em too. Shoup, well, you get the picture. HAd a #41 for ages. Easy to get guards for it.
Kubota B7100, JD Gator 6X4, Kubota L2350, JD 14T Baler, JD 894A Side Delivery Rake, IH 100 Balance Sickle Mower
Those are guards, they are pretty standard, most any farm supply store should have them. If you need them from the net, try sickleservice.com. They have everything, complete knives, guards, ledger plates, hold down clips, you name it.