For those interested in previously unequipped. After web research and eBay purchase, I installed a receiver and programmed the fob on my 1997 850. I purchased items that came from a '96 850 with the FCC # cwttfwb1g both receiver and fob need to match. I checked the fob battery with a tester. I removed the glovebox per Haynes guide instructions and the harness with the green plug was there on the right as expected. The programming was as follows, ignition key off, dash switch locked doors, key to position I, and off 5 times, press unlock on the fob (and second fob if nec.) YAY it works! The receiver unit wiggled into place, but there was no mounting bracket. It's in there with zip tie and tape (would prefer a bracket) Yes, the keyless entry can be added easily.
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'97 855na, Mobil 1, K&N, various IPD's and eBay's

congrats on the keyless install. i just did this recently and it works well. fresh batteries help programming A LOT! (i tried to program for a day or so before getting a fresh batt)

http://www.brickboard.com/AWD/volvo/1262756/850/adding_keyless_entry_central_lock_button_helpadvice_needed.html

cheers!
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-woodsytf '95 850 wagon 157k

Good news. So all I need to do is find a 1995 transceiver to replace my broken one and my little remote will work again.
I am surprised that there was no fitt=ing for the 2 little torx screws that hold it in place. There is no "bracket" that I remember, of course my memory is getting quite bad.

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)