I believe the ones I was thinking of were lower Model numbers; like the 230, maybe. But (unfortunately) my notes from the mid 1980's are no longer to hand. frown

I can't find any pictures of the earliest IVAC's on line either.

However, here are the 531 (drop controller) and 630 (volumetric - and yes, orange):-

Attached Images
IVAC 531.jpg (14.95 KB, 58 downloads)
IVAC 630.jpg (19.02 KB, 57 downloads)

If you don't inspect ... don't expect.