First, I would like to thank all of you for contributing to this post. Very informative and all worked out well on my RX 300. I did have some problems figuring out a way to attached the wire to the lock. As discussed, I was trying to use the post that extends out from the original cable attachment. My problem was that everything I put in there tended to slip out or at least give you the feeling that it would slip out sooner rather than later.
My solution was to buy a couple of feet of Copper grounding wire. Then I coiled the wire around a screw driver handle. This allowed me to slip it over the post, I then took a screw driver and expanded the coils to fill the gap, thus preventing the unit from slipping off. Works like a champ, fits in the hole in the connector that comes with the new unit. Anyway this is my contribution and will hopefully help someone else out down the line :-) Picture attached.
Rick