I left my cuda sitting in my yard under a car cover with no trunk floor, a cat had a litter of kittens in it.
When I removed the car cover it smelled like cat piss bad, I bought a bottle of Urine Remover from Lowes, sprayed it in the whole car, and hosed it down. Let it dry overnight and it had no smell what so ever.
You may want to consider doing that to the heater box, before you assemble it, the stuff amazed me how well it worked.
