Speedo woes

[manualwagon]

Hi all. Can anyone tell me which speedo drive unit should be in the trusty wagon? Its a manual 3 litre exec that started life as a bog standard unit, but at some stage of its life it was given a set of 15 inch 5 spoke alloys. I treated it to a calais dash and today checked it against a GPS unit. At an indicated 80ks the GPS showed 72ks, 8 ks under. [explains why i used to get so many greasies on the daily commute]. Any idesa please. John

[harry3]

ask the local wheel shops what to do as it must be a common problem