Which outer CV joint kit

I have a 1991 GTI rivage and need to replace the CV joints and am having issues with which kit i need. 
I bought a kit and took it to the mechanic to be fitted. I was told that the i needed a 90mm joint not 81mm.
Spoke to VW heritage and they only have 81mm kits; the only difference between them being the size of the driveshaft.

Can someone advise what i do need - thanks!!! 

I've just had issues with Meyle outer CV joints for my 1983 tintop GTi. They binded against the inner bearing housing when the axle nut was tightened. I've just got GKN Lobro ones and they are spot on, although much more expensive. I got mine from Eurocarparts. You might not have the same issues as me though if yours is a later model cab as I think bearing housings changed.

a 1990 cabriolet GTI has MK2 GTI CV joints

driveshafts are whats known as '100mm' which is the outer diameter of the inner CV joint

Pistol the problem is you were supplied with mk2 golf outer CV joints, which are too big for tintop wheel bearing housings.

after 1984 the housings were modified to accept the larger MK2 golf outer cv joints