Aloha,
Over the years I have seen some nice and not so nice P-38s at wrecking yards.
The one thing the breakers don't know is the mileage of the Rangies.
If you happen to have a Nanocom and a suitable battery, you can not only determine the mileage, but also test the stereo / amps
and unlock the doors, tailgate, and lift hatch without destroying anything. And without the key.
I recently had amazing luck reading the mileage on an 99 that had the dashboard and all the electrics therin
removed by what appeared to be a dull shark! A total shambles.
As I wanted the rear diff, I wanted the mileage, so using an 18v Makita cordless tool battery and a set of leads and clips to fit,
I gave it a try. To my astonishment, it lit up and I was able to read the information.
Just clip an 12-18v battery to the battery leads and fingers crossed, it will play!

A good hint although a P38 is very rare in a breakers yard here, they are all bought by the specialist breakers to be stripped and the parts sold off on eBay.... I was wondering if simply giving the Nanocom a 12V supply through its power socket would be enough, but thinking about it, I suspect the BeCM would need some power if it was to be interrogated.

Yes, I'm sure the Becm needs to be powered up.
I got even luckier as someone had pulled all but 4 of the small fuses and had left only one maxi in the under bonnet fuse box. Just enough apparently.
I will have to add a few Maxie's to my kit as pulling all the fuses is common.
Even luckier, even though the passenger side foot well cover was hanging out of the door by the Obd port wires, they were still connected!
P-38s are a bit thin on the ground lately, but if you are in the San Francisco bay area, there always seems to be a couple around. Sadly that's 12 hours drive from my place now.