I seem to remember reading somewhere that from the factory chassis's were being painted O/Drab, the chassis on one of my 109's was Olive Drab, not just the outside bits you see, it was all over as you can see in this image

the chassis was on a jig at the time and had been pressure washed, to reveal the Olive Drab paint, cheers Dennis
ps my personal preference for chassis n diff's etc is Gloss Black,,. like this

this is 113-372.
Here are 2 images of my 109 Wksp rebuild job, with my old mate Graham D inspecting the work LOL

here is the same chassis partially painted in Gloss Black

refitted with Salisbury differential

hope they are of some help, cheers,,.