can someone explain how these desinations work or where to find more info' "PR-OBD" "PR-OBE" "PR-OBF"

These are codes for the rear anti roll bar,different codes for different sizes as follow:

OBD = 19,6 x 2,6

OBE = 20,7 x 2,8

OBF = 21,7 x 3

Hope this is what you were looking for ...

Normal, Sport & vRS?

These are codes for the rear anti roll bar,different codes for different sizes as follow:

OBD = 19,6 x 2,6

OBE = 20,7 x 2,8

OBF = 21,7 x 3

Hope this is what you were looking for ...

thanks for that it looks like a spec as it seems to be constant to arb's size even when the part numbers change, also a common designation across makes -- I'll get me' anorack :-)