I believe the 6 diode models are the Optix heads. I have several in blue available, if you can get a pic of the exact modules you are looking for that would help. PM me directly and I'll send you my email address. Thanks, wolfman
Do they need to be Whelen 900s? I have a NOS set of four Code 3 Prizm II 9x7 split red/blue with clear lenses.
PM me directly with your email if you are interested...