In this video, John shows a roller chain from a front mounted snow blower off the tractor that has a roller chain connecting link break. The original chain was a #40 but had seals or gaskets to keep out the water/snow/salt for a longer life on the blower. Common replacement roller chains do not have gaskets and the width is different from chain to chain.

Roller Chain #40 From A Snow Blower With Gaskets.. Uncommon Roller Chain Differences