2011 27" iMac Hard Drive switch with sensor

I know this subject has lots of coverage. I'm aware of fixes with grounding the 2-7 Sata pins to disable the drive sensor and using software to control fan speed and yes, this is part of an SSD install. The local Apple Service Provider says they install a separate sensor such as this:

http://applecomponents.com/items/92...-optical/0000004398?pn=1&cmp=0172&per_page=30

(I'm not sure I have the right part). Has anyone done it this way or know what parts are necessary ? They charge $90 for the sensor and $50 above the fee for adding an SSD so total is $300. It's a little on the steep side for adding a sensor but when I tried my iMac surgery, it wasn't much fun.

I have a Seagate Barracuda 3TB I plan to install. I'd also read if you bought the same brand drive as you had (my prior 27" iMac had a 1TB Barracuda) that the sensor may be in the drive and setup already. Of course I'd prefer to do this work once and only once so I thought I'd see if anyone else has tried this.

Thanks in advance

Ben

Replacing my 1TB Barracuda with the 3TB Barracuda did indeed spin up my fan. I finally bailed and took it to the local mac repair ship that had a German retrofit part that contained an actual temperature control sensor. The part was $90 so it makes for an expensive extra 2 TB. Sorry, since the shop did the install, I don't know the exact part but I did see a few with a brief search so they're out there, just not easy to get.