I cant seem to find a definitive answer for this. 99 40hp ELPTO Fuel Pump Diaphram(s)

[dacostadesigns]

I am rebuilding the fuel pump on a 99 40hp ELPTO. The kit comes with white (plastic diaphrams - check valves) and Black rubber diaphrams. Which do I use? Manual say one is for design 1 and the other design 2. It does not tell how to identify the design you have. I have found a lot of mixed answers - including using both. I also do not know what was on there originally.
I appreciate the help!