Ok Phil and anyone else who may find this useful
First the cost, 29.00 euros from Grootspoor, that's where i got mine from, as part of a larger order....
It comes with instructions, in various languages but not English, and they do not produce them in English, but i found Dietz helpful in providing info by Email,
as i had a concern over voltage and blowing the diode. Which turned out not to be a problem.
Sizes
Circuit approx -- W 15mm L 40mm H 10mm, excluding the diode wires approx 25mm and 450mm tails.
Lamp approx - - W 10mm (at widest point (it tapers)) H 15mm (over loop handle) D 8mm.
The diode has a square end with a ctr pip for the want of a better way to discribe it, that is a loose fit into the recess on the back of the lamp itself.
In fitting it to the coach you need to dril a 7mm hole in the coach wall for the diode head to pass through to the lamp, or i guess you could cut the diode free and solder extensions to it on other vehicles,
i guess it is a soldered connection to the circuit board, but i did not remove the thick shrink wrap to see.
Lamp itself is a hard brass or alloy painted (I think its actually an overlay of some sort on the front) as in the photo with the rest of it grey, i drilled and tapped the rear of mine so i could fix it to the coach, rather than glue the diode to the lamp as the instructions state, thats how i found out it was hard.
It will work on both DC and DCC.
Whilst on DC it is not polarity dependant, it takes longer for the capacitor to charge on reverse polarity. DCC is a allmost instant start up.
On both you get a gradual build up in the intensity and rate of the flash until it settles at the rate in the vid link above.
Should add because of the capacitor in the circuit, it will continue to flash for some time after power is switched off, approx 10-15 mins in my case,
i did fit a switch to the underside of the coach so that it can be isolated.
The cast iron test as far as i am concerned, would i buy another one........Yes..