Right ok the previous owner claims to have ran it for years with no issues so maybe it has been done take it there is no quick easy way to check without taking the head off ?

The difference is unleaded requires hardened valve seats so they don't burn. If you put additive in to a head that's had the valve seats replaced then all you're doing is wasting money. There's mixed reviews on how much good the additives did...

Hi all ive just got a series 3 1974 first petrol one I've had, is there anyway to tell if an unleaded head has been fitted. From what I know most of them were leded heads and it's the 2.5 where the first unleaded heads came in. So I'm not sure...

Love it this is something i am also looking to do. Did you add the rear bulkhead to the back tub to make the pickup roof fit ? My station wagon doesn't have one between the second row and the rear tub.