Max Muller wrote:
I have an old W510 with Fan Error and when I power it up with
the keyboard out, I can see the fan spin for a second, and then
shut down (I already blew all the dust out).

http://i.cubeupload.com/PPtURP.gif

I think I'll replace the fan, but I want to get the right part
number.

There are two similar part numbers.
Which is the right part number?

FRUNO: 60Y5493 P/N: 60Y4981

Where do you get your parts?
What is the correct part number?

The correct fan and part number depends on which one is in your machine.
It could be either depending on graphics chip.
I get all my Lenovo parts from Ebay.
Go there and compare fan pictures to yours.
Btw, IBM sold their laptop business to Lenovo in 2005.