Tonight I pulled out the transmission (it’s surprisingly easy) to allow access to clean and paint the area above/around the transmission. With the transmission out it was easy to see what had been blocking one of the heater channel entry points just above the transmission, a mouse! It was basically mummified so I’m sure it had been there since the bus was stored outside. Also, over the weekend I had cleaned/painted the underside of the belly pans but didn’t post or take any pictures, so I took a picture of the underside tonight.
