For those of you who have only an Oil Light in their car, and want to install an aftermarket Oil Pressure Gauge, this may help you out.
My GP has only an Oil Light. I got a pressure gauge for X-mas. I wanted to keep the oil light functional, just in case the new gauge decided to stop working for some reason. In order to accomplish this, two different oil pressure sending units are needed. The stock one, and the one that came with the new gauge.
From a local parts store, this was purchased.
The new sending unit it shown connected to a steel braided line with some different hardware. The goal is to remove the exisiting sending unit, put this new fitting in place, and then be able to connect both sending units to it. The steel braided line is long enough and strong enough to put it anywhere that is feasible, and it won't go bad.
I don't know if the location of the sending unit is different on other 3800'*, but for the Series II engines, it is accessable from the passenger side wheel well. It is kind of hard to reach, but you can remove the old sending unit with lots of patience. It is also advised to remove the power steering line if it gets in the way.
This is what it looks like with the new hardware installed. Make sure everything is sealed tight.
The steel line was ran up in to the top of the engine bay, then connected to the steel area near the firewall. My dad thought of a custom way to mount the sending unit. It can be mounted anywhere available.
Once the new gauge is installed, turn on the car, and everything should be working fine.
This gauge install could have been done easily with just one sending unit, but I wanted to keep my oil light just in case.
I hope this helps out anyone who is looking to do something similar to this on their car.