I have one of the original (or close to it) 36" griddles that doesn't have a serial number and have aways thought about adding a top like this. It fit perfectly and serves not only as a cover but also a wind break when cooking.
Great fit and easy to use, not overly heavy. Helps protect the side of my cabin from heat and grease splatter as well. Definitely worth it to keep the griddle clean between meals without having to throw the soft cover over it each time.