I bought my replacement windshield gasket on Ebay. I'm not sure if you don't already know, but when searching for things online for your truck you have to state "RN20" because what the pre-75's are referred to. I know a lot of guys who miss out on bits for their trucks because of this. If you don't find one right away on Ebay, be patient. They do periodically pop up there. One week you will see one, then you won't for the next week or two. But they someone will eventually offer one up shortly thereafter.

Good luck.

Joe