I've got a clock from an old 1983 Mercedes van that a friend was scrapping. It fits in pretty well as it's made by VDO, keeps perfect time and best of all, was free!
As an aside, I also found that the window winders from an '83 Merc van fit a camper and are MUCH stronger than the replacement ones on sale form some specialists.
My '71 Deluxe has a (non-working) clock. I want to remove it and fit a tach, but in such a way that the dash is not damaged, and so that the clock can be put back at any time. Haven't found a nice (correct size) tach yet though. I also want the 'font' of the lettering of the tach to be more or less the same as that of the other dials :wink:
I had a blanking plate, so I made it into a clock with one of those square black battery clock mechs you can buy for pennies. See 3rd or 4th picture down http://www.mystuffonline.co.uk/5.html
Also colour-coded all the dials, and made a fancy 'VW' logo to go where the speaker holes were on the dash top.... (next picture)