Anybody know where i can get any good ones from?

what speedo you got?

http://shop.ebay.co.uk/items/_W0QQ_sopZ12?_nkw=rare+earth+magnet&_sacat=0&_fromfsb=&_trksid=m270&_odkw=bay&_osacat=0


the bay of fleas of course

VDO and sensor mounted at the back off the diff

IIRC RS sell many, small thin discs.

I've got loads of small disk magnets, approx 12mm x 1mm. they seem to be very strong - will hold each other across my thumb. We don't need them at work so they will probably go in the bin.
You can have as many as you like (within reason).
I will post but to save the bother of payment, I'll do it for free so long that you promise to make a donation to the red nose appeal (text 88808, costs £1).

Any idea how to post magnets without the envelope sticking to the royal mail sorting machines?

Sent you a message! Cheers!

How about ETB as they are agents for VDO, I would use the disk and sensor fixed to the diff though.
http://www.etbinstruments.com/Sensors_ancillaries.htm