I just installed an old Spa gauge and thought I'd pass it on in case anyone wants to have a pressure/temp gauge in their Pentastar. Before anyone says the sky's going to fall I did the same thing on my Sprinter several years ago. In fact the gauge came off my Sprinter when I sold it and saw no reason why I couldn't do the same thing with my jeep.
I'm not going to get into every detail. I simply drilled then a 1/8" pipe tap in the center of the filter cap. I used a o-ring and teflon tape then screwed it down. On the bottom side I used a nut. Yes a nut will fit using a socket but I had to grind the socket down to make it work. Snugged everything down well but not over tight. I would have used locktite but didn't have any. I'll keep an eye to make sure there aren't any problems.
I'm going to buy a new filter cap and keep in the Jeep with a wrench in case I have a problem on the road. I'm also picking up another oil pan drain plug and will drill/tap and screw the temp sensor in. That way I have a fully functional gauge. It will be nice to monitor oil temps even if it only show's pan temperature.
I'm leaving the engine cover off in case someone points out I'll never get it back on. I could have put the sensor sideways but thought there might be too much leverage on the cap. The good thing about this mod is that it's easily reversible, but I did have to cut a hole for the gauge.
There you have it. A simple and effective mod that you can undue any time you like. If you try this I'd buy another cap first in case you screw one up, and carry a spare in your Jeep. The last thing you want to see is smoke pouring out from under the hood