If you use a cap with a Motor Meter, like the one above. You will have to remove the cap prior to opening either of the hood doors. It's a real pain because you will most likely forget and damage the door paint.
As far as I know no one is making these anymore but all you need to do is drill the right hole for the motor meter you are going to install. Repro winged caps are in the $300+ dollar range. If you can find someone. I have seen them at Hershey.