Details & Changes.

Body number.

From chassis number 20-027226 the "Body number" is stamped on the front
bulkhead on the right side. Before that the chassis and body number was
the same and was stamped on the right side, in the engine compartment.
It's hard to see the location of the number so it's been circled with red
marker. See picture below

This number is from my own bus, which has chassis number 20-063506.
I can't explain why body and chassis numbers aren't the same.