Thanks James
The part no.you have given me I have already found .
But they both run 10-180ohm which will make the Hz gauge read backwards.
VDO do list one that is 240-33ohm but it run a 1/8 NPT thread instead of the 1/4 needed, I can run an adapter
But have previously bought the one I need with the 1/4 thread.
I think I'll go to the local repco and dump my problem in their hands ,then jump up & down when they get the wrong one.
Thank you all for your help..