drive shaft help

hi all my 1989 mk1 golf gti clipper has recently started to knock from the drive shaft i want to change them but iv seen there are 2 types 90mm and 100mm can anybody tell me witch i need cheers sam

Can't see a driveshaft knocking unless it's bent, do you mean worn cv ? To check which type you have fitted remove the shaft and measure across the flat of the gearbox flange

yh its the inner cv i was told i needed the a new cup but was also told there a ball ache to do so i was gonna get the job lot

I need to change all my joints and boots, where's the best place to get these? Are OEM new parts still available?