speedo help!! driving me crazy!!

problem!
ive got a mk1 with a 20vturbo witch is running with a mk4 gti gearbox but i cant get a cable to go into my mk2 16v clocks that are in it.. been told i need a early corrado speedo cable from a 18.16v but i cant find one. so if you no what i need please let me no. ive also picked up a set of 20vclocks would these be easier to use as i was thinkin about a custom dash, at lease i no i can get the speedo cable but then will every thing else wrk!! help me i'll be total crazy soon lol

My MK1 20V uses a 1990 Passat cable .

Fits a treat but reads 10mph fast .