Im trying to find out if my donor pinto engine is suitable for unleaded fuel. I believe I am looking for either the letter L P PP R or RR just behind and above the No 4 spark plug.

I believe No 4 cylinder is furthest from the rad/front of the car can somebody confirm this please.

Can somebody also take a photo of their identifying mark/s so I can see where to look as I cant see any mark at the mo.

What other letters did Ford use???

yes its the one at the back
on mine its was a letter stamped on the flat section next to the spark plug
i could only see it when i cleaned it up with some emery cloth
good luck dave

Cheers dblissett, could you take a photo of yours please so i can see