Planning the next
AO Silver Member
Join Date: May 2007
Location: United Kingdom
Other than for the side of the car ( left, right ) there are two versions of regulator as you have found.
One is for cars made before June 2000 and is sometimes referred to by sellers as '2 pin'. The other type was for cars built from June 2000, These regulators drop the window a little when the door is opened and raise it again when the door is shut. These regulators are sometimes referred to as 'autodrop', 4 pin or as having a microswitch.
So, if your car was built after June 2000 and the windows normally drop when the door is opened, you need the microswitch version ( autodrop, 4 pin ).