I recently acquired a air horn kit from a 1979 ford f-series with a vacuum powered compressor pump. To install, i have to put the pump into a vacuum line as seen here (http://postimage.org/image/89erlowsn/). Which vacuum line should i tap into for this install? Any help would be greatly appreciated.
-Jm5

 

How about tee off the line to the power brake booster? It's the biggest and you know it's a good source of vacuum.