Reused the bolts that were there. Seemed factory but looked like three different brands/stamps

I used Justice Brothers Engine Degreaser. Seemed to work better than brake clean or concentrated simple green. It was best when surface dry between applications/follow-ups. I used an air nozzle to dry. Then scrub. Then spray with hand spray bottle with water set to stream. The agitated greas-grime and degreaser would shoot off surface when the shot of water stream hit it. Then slide and dip off to a pan underneath.

Used dishwasher brush, small stiff bristle shop brush, engine cleaner bottle brushes.