any idea where this rubber piece goes?

The bike was idling in the drive when I noticed this part on the ground....it was laying on the left side towards the front but being rubber I'm sure rolled around some. I have had the bike on the lift and cant see where it may have come from. Its small...just under 15mm diameter and 14mm long. Bike is a 1974 mk2...obviously not a critical piece but it does serve some purpose. Just noticed with the pic blown up it appears to be pressed in someplace...think I will have to remove the tank to look more closely

Have a look under the steering stem and see if the rubber bung has come out before you take the tank off.

You were right on the money Mark...thanx, owe you a beer