The photo would show you the shape of inner alternator shaft. If it is Torx shape (6-lobe, Star), then you need T50, or if it shows 12 splines (double Star), then, You need M10 XZN bit. 17mm Hex with 33 tooth Spline PLUS M10 XZN bit.
Combined Alternator Clutch Removal/Fitting Tool, 33tooth Spline +T50 Torx Star
Combined (TWIN) Alternator Clutch Fitting Tool, 33tooth + T50 + M10 XZN Bit
33 tooth Spline Alternator Clutch pulley Removal/ Fitting Tool - 17mm Hex
VW VAG Alternator Clutch Free Wheel Pulley Removal Wrench 33 Teeth Splines Tool
