last week i bought a 1983 200T in the UK, and i have no idea what fuel i should be using. previous owner doesn't know, he only had the car one month and i haven't yet traced an earlier owner.

is there any way i can tell which i should be using, my car is pre-catalytic, which makes it leaded, however apparently most people had them changed over. how can i tell?

until i find out is it better for me to be using one or the other from a damage containment point of view? what damage might occur if i continue to use the wrong fuel?

many thanks in advance, jab