I see conflicting information online about the m952v. How do I tell if it's the 350 or the 150 lumen version?

Comparing the 2 M952V I have "one of each", the older 150 lumen heads have a blue tint to the light, while the 350 Lumen head is a brilliant white light. IIRC the 350 lumen has a square laser etched data matrix on the head, while the older one does not. It's probably best to contact SureFire Tech department to find out for sure, since they have been updated over the years. Also they should be able to tell you at what serial number did they start making the 350 lumen version.