Thanks for the quick response! Is that a typical part number format for DiMarzio OEM pickups? Does it give any indication of which guitar manufacturer they were made for?
I have a fair number of older DiMarzio OEM pickups, but they all have just a stamped-in code like "N1" or "B-2". Makes it difficult to know exactly what they are or who they were made for.
Yes, there are exceptions, but I'd say that's been a fairly typical format for quite a few DiMarzio OEM models produced in the past 10-15 years. The physically stamped ones tend to be a bit older ('90s-mid 2000s).
I've had quite a few OEM models pass through my hands and figured out fairly quickly that when you see 2 digits in the middle of the part number, they generally coincide with the last 2 digits of the model it is.
So "91" pins it as most likely a "DP191", the Air Classic Bridge. If you take a resistance measurement on it, I bet it aligns with the specs shown on DiMarzio's website.
Hard to say who it was made for, unfortunately. Could be Ibanez, Ernie Ball, Yamaha, Godin, or another, smaller builder. DiMarzio may be able to give you more info if you contact them.
Side Note: I have a set of DiMarzio/IBZ pickups sitting here that have "B1" and "N1" tucked away in the part number on the same type of label. I had a set of Chris Broderick sigs from a Jackson that said "CB1" and "CB2" in the same position. I've also seen OEM-supplied Virtual PAF models from the 2010's with labels like this that said "96" & "97". Sometimes OEM pickups just have the standard part number and sometimes they don't give any indication of the actual model (more common with Ibanez-supplied models for some reason).