I was wondering the same thing as SteveH above with using only one converter for both meters, but I wired mine exactly as GJR did here. 
Previously (way back before the AC meters became unavailable for several years), I sacrificed a couple of volt meters using an AC to DC converter in my copy of GRJ's voltage car so I could learn more about DC to DC converters (again thanks to GRJ). 
I was tempted to try using only one DC-DC converter here, but from my past experience decided to defer to 'others' for any further sacrificial meters.
On the brighter side, these newly found meters seem to ship rather quickly after ordering, replacements will arrive in about a week! As I recall, it took a month or so to replace mine for the voltage car. 
GRJ, I ordered more of both the meters and the DC-DC converters for future use. (Once again, everything arrived in about a week, nice!) I looked around a little at DK & Mouser for some possibly lighter duty and less expensive DC converters for stock, but these were hard to beat from what I found.
