In the 01 diesel chassis frames were a couple of odd cutouts in the top edge. I had a good look at the plans but couldn't see why they were there. In fact, I had a good old think and they remained a mystery.
Then I built the body and plonked it on the chassis and all became clear. They are there to clear the bolt heads that hold the bonnet/cab assembly to the footplate.
That's a really clever detail. You can't see them when the loco is the normal way up so there's no need to solder the two lumps together and then remove them. I like this sort of thinking a lot. It's the sort of thing that encourages confidence in the rest of the range. Well, if I didn't look at the rest of Mike Edge's kits and want to build them all anyway !