Heater box seals

I've rebuilt my heater box and away to fit to my new bulkhead.

I've got the seal that goes inside the heater box, but it sticks out quite a bit. Is this correct? Does it just get compressed against the bulkhead to create a good seal?

I was watching Toolfitters video on youtube and he mentioned two seals - one on the bulkhead and one on the heater box, but i could not see clearly where this other seal goes.... or find the part...

Any help appreciated.

I've just done mine and had the same problem, don't no if it is correct or not but I cut a peace out of either side of the seel ( about a cm I think), glued It back together and siliconed it to the box so it fitted correctly around the box opening, then the next day fitted it, all seems good , good air flow and now gaps

Haha that's one approach. I'm not keen on cutting the seal though - i'd imagine its that size for a reason...

I seem to remember another seal kicking about, but I cant find anything about it now.

Anybody got any other ideas?