Lenovo FRU 13n2950 or 2951 fan spec

You can buy the fan and heat sink assembly from many vendors: I'll assume that the label on the fan has no useful info or is missing. You can measure the case size with a ruler. The fan power is probably 12V and you can measure the maximum current by just applying 12V to the red and black wires and measuring the current with an ammeter, leaving the white wire unconnected. However, there's the problem of whether the third wire supplies tachometer feedback (i.e. speed info), or some kind of pulse width sensing. You should be able to determine that with an oscilloscope. Then, you get to sift through data sheets trying to find a suitable match. Unless you need a fair quantity of fans, I suspect that you will find it easier and cheaper to just buy the assembly:

I've never known a ThinkPad fan to *not* be 5v before. I guess you learn something every day.

The FRU 13N2590 is a desktop FRU. The thinkpad group was "fishing" for a knowledgeable repair person for Lenovo.

Ahh, ok. I guess if I'd looked at the fan size I would have maybe noticed. However the "12 Volt" thing jumped out at me first.

w/r/t desktop fans I just match physical size, number (and function) of wires and rated current draw or volume of air moved. Sometimes only a few of the preceeding. ;)