anybody know what size fitting i need to use the vacuum port on the rear of my performer 600cfm?

thanks!

If you bought it new, it should come with a small black threaded plug that you can install in that port. Just take that plug to the parts store and match up the threads with the proper fitting. It's also the same thread as a Q-Jet's similarly located port if you have one lying around....or if you have the vacuum line from a similar year GM power brake booster.

good point, i will do that!

Should be a 1/4" NPT thread size.. Ace hardware or any hardware store for that matter will have plugs and hose barbs in that size for under $2.

I got mine at Ace.