UKSaabs

I'm currently restoring the underside of my 72' Saab 99 2 door and have peeled / chipped / wire brushed off all of the underseal. Not too bad a job and not too bad a condition underneath considering the car's age and that it probably hasn't been stored in a garage for much of its life.

I do have some rust holes to make good with fresh steel and one of them is a hole that has appeared at the top of the passenger side rear spring 'turret'.

The rust here has developed in the seam between the 'turret' (or whatever its called) and the inner wheel arch which, on the other side is inside the boot space.

The repair will need the soundproofing material removing from the inside of the boot to be able to cut out and weld fresh steel in which is no problem but, what I can't seem to find is - what is the soundproofing material?

It looks and feels like the self adhesive bitumen material that the likes of dynamat sell but, it has a grey leatherette textured vinyl face to it to match the boot floor vinyl carpet.

Has anyone found a source for this stuff or anything close? I don't really want to put smooth black pads back in and paint them but, they do look a bit rough and one side will have a square missing once I've finished.