Replacement tubing necessary due to rust. Nice work Tim. You could actually poke holes in the old metal with a screwdriver. I hope the rest will be OK. B9/001 was a prototype so holes were drilled to attach things, Then they'd decide to put an item somewhere else, facilitating another set of holes, leaving the old holes. So it's a pretty holey old chassis.
B9/002 is a prototype too. However, it doesn't resemble B9/001's chassis much, but then again all 12 chassis seem to be a bit different to each other.