I took the E-vac rail out of my head i was wondering if anyone knew the thread size so i can buy bolts to plug the hole, thanks

 

Are you talking about the smog tubes? What motor? On my 4.9 I needed 6- 1/4" NPT plugs.

 

The small holes that come out right above the exhaust manifold and tape into the exhaust port, its a 87 4.9L L6, sorry shouldve mentioned that

 

Back in the mid seventies when everyone was taking that junk off, auto parts had the designed plug with the tapered end to seat into the hole. Believe it was a 3/8-24 thread. The 1/4 NPT plug will work just fine. The auto parts fix was pricy. BTW, that system is called thermactor and it was more problems than it ever cleaned up emmissions.