Outer heater box caulk - non AC

[Green Machine]

Putting the outer heater box back on a 70 C20, after cleaning and new core. This is the third one we have have done. We usually use the strip caulk the type you peel off a roll and stick to the box, about 1/8 in diameter per string.

Using one piece of strip caulk hardly fills the gaps in spots, and using 2 pieces gets so stiff you can't press the box to the firewall. So what about some acrylic latex "house" caulk in a tube, I think it could make a huge mess but..

What has everyone else used ????

[ETsC10]

I've always called this stuff Dumdum and maybe it's available in different diameters. I would think an automotive paint & body supplier could send you in the right direction. You can even go to the wrecking yard and collect the stuff; roll it into the right diameter and there ya go...
Regular caulking may or may not work. I'd think using the appropriate automotive grade (dumdum) would be better...it's designed for the application. BTW-all caulkings are not the same...research before buying, if you chose this route, as the cheap stuff will only cause you grief.

just my 2 cents....

[OhNoJoe]

http://www.frost.co.uk/item_Detail.asp?productID=8317

Is this the stuff?