Thought I would give a little update after some further research. As mentioned in a previous post I did install a pertronic kit and 18 months later it hasn't missed a beat.
I have gone back and matched the mercedes distributor with corresponding unit which used the same pertronix module as the trusty grey. I then went to
http://www.hot-spark.com/1-Bosch-Distributors.htm which I made mention in a previous post. It now seems that they produce a kit for the corresponding mercedes unit hence the grey. The kit number is3BOS6V2. Now at $59.99 with $26 (US) postage if anyone is after a cheaper option than the pertronix, this kit maybe the way to go. With the Aussie $ on almost parity with the us, I might order a kit and keep it as a spare at that cost.
I hope the info is of interest.
Rod