non genuine speedo

Ive been having trouble with the speedo in the kalita of late, its a VDO, I sent it in for repair some time back as the odometer stopped working, had a new bezel fitted at the same time, well 12 months on and I got around to refiting it in the car but noticed that the trip meter wasn't working so removed it and took it back to be rectified, (done under repair warantee) well it lasted another 142 k's and then the speed was registering as around 60 when in my estimate I was doing at least 100k's, the odo and the trip stopped working, so it's back to the repairer again (registered VDO people). I'm thinking its stuffed, so I'm thinking of a full replacement, digital may be the go, the hole in the dash is 80mm and not much else will fit, maybe a little larger but not much. any thoughts / recomendations?
thanks
Don

You could use one of these, you will have to adapt the pulse generator to the speedo cable, I two different brands in my cars, Autometer and Pricol, both are easy to set up, these are 85mm in diameter, I doubt the GPS speedos are legal as they drop out in various places , even though they are easier to fit I would still go with the electronic speedo, they have proved very reliable in my case..