Jeff, if it is a 30psi max output, the part number should be 3152...., but I don't see the part number on bigtrout's 315, are you sure it is a max 30psi output model? or may be it is a 50 psi max output model, the low pressure gauge is 60 psi.
According to the "sold" item on eek bay matching his.
That guage also went up to 50psi-ish
If his had a hose barb out originally then the model is
NEW Concoa Regulator 3152391 Dual Stage CP Brass CGA 320
TOO rare of a combo to not be it..
Chrome plated brass
Let me check the spec sheet.
315(A)(B) (C) ect
A = 2: 0-30 PSIG(0-2 BAR)
B= 3: 0-4000 PSIG/0-275 BAR
C = 9: 1/4" hose barb
D = 1: Standard assembly(PSIG/kPa gauges)
Many Victors, as you know add 2X max outlet gauges on the lp side.
Gauge markings are practically meaningless, especially with used items.
Don't get me wrong, still a good find w/ a "possible" minor limitation.
I love new or New Old Stock
Reason I decided to "snoop"..