Hex collared bolt M8x45. This bolt has various uses, some of which are listed below

Mk2 Golf G60
Used in the supercharger assembly

Mk2 Golf and Corrado
Used in the engine subframe mounting

Mk3 Golf
Used in the subframe assembly on the following models
1.9 Diesel 1Z
2.0 16V ABF
2.8 VR6 AAA

T4
Used in the gearbox assembly