Stink pipe covers for 1970 Safari

I recently purchased a 1970 23ft Airstream Safari. What I can only think of as the stink pipe outlets coming out of the roof are just bare black pvc with some sheet metal and goo loosely fitted around them. There doesn't seem to be any major leakage but I do need to address this. Does anybody have tips on how to finish this off properly? Maybe some decent pics or links to where to buy replacement parts. I am new to rvs and this is my first of many questions.

Peace and thanks for the help.