After removing all the underseal from the rear arch...
I started on removing the underseal from the front arch.
I unscrewed the expansion tank; one of the pipes at the bottom just snapped
I disconnected the main fuel pipe from filler hole to tank, just pulled away, not sure if that was OK? But it's out of the way for now.
Think the tank may need to be dropped at a later date.
Anyway found a few holes under the front arch.

1982 Diesel hightop. 1Y engine. Still work in progress but running and taking us on holidays.