A friend retiring from the Porsche repair business is cleaning out his shelves and among the other rarities, he had a 959 speedometer. It's in like new condition. And it's in MPH...
I've asked around and people have suggested values from $350 to $12000.
I just gave up and put it on eBay.
Porsche 959 speedometer - MPH Super Rare, like new | eBay
He also sent me a 935 boost gauge, which I'll be putting up for sale. So far, *nobody* has suggested a value for that puppy.