I sold my '77 F150 and bought an '89 F250 regular cab, 4x4, 5-speed, 7.3, with added ATS turbo (with waste gate and down pipe). So far I like this truck.

On the side of the ATS air cleaner box is a threaded fitting. Anyone know its purpose? I was wondering if maybe for ether injection? My neighbor thought it was for vacuum gage for measuring boost?

Any ideas?