@Noddybrian....thx for the photo. I have narrowed it down to needing the 90 degree fitting in your pic. Any idea where I can get it, what it might be called, or if there is anything special about it?

Thx

After some further digging and some help from YouTube, I find that the guage I need is built into the front and what is missing on the back is a 90 elbow. So I'm a little closer .....Thanks @Braehill

Related question for the discussion........I bought the MTN Gearsmith CT520D and had a similar thought of buyer remorse when I saw no plug. left it in the box for a couple of months and only just now decided to figure it out. I got the plug installed and seems to work but am struggling with the air ...