I don't know about the suspension but in the late 70's I ran the leadoff machine for the caseline. We used a small refillable plastic bottle with a top that had about a 1" fiber wick to mark which head on the machine the case came off of. The color we used depended on the shift. I was on afternoons and we used green. the other two colors were black and blue. Also it wasn't paint we used it was ink that came in gallon jugs. Steve