Strange hole in the foam

It’s a good thing I dismantled the heater notice the dirt and leaves that came out of it.



The upper part of the heating unit, quite simple to disconect from the lower part.
You just need to drill out two rivets.



I will replace this plastic by a proper foam.



This is wat's left of the old foam...

On the back side of the water pipes foam there’s an impression of something but there is nothing on the metal plate where it was positioned so what could be the reason for this impression. Has somebody been working on the heater before?

I don’t think so because the car has only 50 000 Km and when it had it’s re-spray the heater wasn’t removed because there are spray marks on it.

Or did they at Speke use foam that already was used for something else?
I’ve been amazed by the sometimes poor building quality like welding and the lack of any rust prevention but even when the car has been completely stripped and you think you have seen it all another surprise pups up.

That’s what I like about these cars; the more you know about them the more you become aware you know nothing at all.

OK I apologise I just found out that the foam has original three holes (see Rimmer catalogue) I do learn each day.
But what's the third hole fore?