Classic/Antique Car Repair: vacuum loss, ford meteor, ebay

Question
I have a 1975 Ford Meteor with a 460 engine. Lately i have been hearing a hiss when the car is in gear, none when in neutral or park. There is some kind of a vacumm boost near the parking brake. It is leaking. The car runs rough of course. Can I plug the line going to the thinghie, or should I try and find a replacement.
If I block it, will it affect performance?

Thank  you

Answer
What you are hearing is a leaking diaphragm in your automatic parking brake release.   You can disconnect and plug the hose, doing so will restore your engine to normal operation, and will not cause any problem at all, other than the fact that you will now have to remember to manually release the parking brake before driving off!

If you someday find a replacement brake release device, you can install it yourself and be back to like new operation - I have recently had to do exactly this on my 67 Imperial.

I found the replacement brake release device on eBay for about $20.

Good Luck

Dick.