The plan was to purchase a tube for myself, and make the part number available for others who wish to try it.
I did a little research tonight and came up with this:
"An alternative to muffler putty would be a silicone sealant. We have one product that I have used in the past with a fair amount of success. This is Loctite 596 Superflex which is a sealant that is capable of withstanding continuous operational temperatures of 315°C. If they are exposed to temperatures above this point they will char, however the charred material will still provide a seal, and will allow separation for service. "
FYI: 315*C is 599*F
Theres also this stuff:
"PERMATEX ULTRA COPPER Hi-Temp RTV Silicone Gasket Maker
For turbocharged or high-performance engines. The most advanced, high temperature RTV silicone gasket available. Sensor-safe, low odor, non-corrosive. Superior adhesion. Three times more oil resistant than conventional silicones; eight times more flexible than cut gaskets. Temperature range -75°F to 700°F intermittent; resists auto and shop fluids and vibration.
Suggested Applications: Exhaust manifolds/headers, valve covers, oil pans, timing covers, water pumps, thermostat housings Part# 81878 3.0 oz."
I'll still try to find the 3M part number if I can, but these seem to be suitable substitutes. I like the Loctite over the Permatex ultra copper stuff, however...
Ryan