I got some new front rotors for my 71 from PP.

They are part #411-407-075-M294
The PP site says these are correct for my car, but the box (Sebro) says VW 61-70.

AND.... they dont fit. The "hat" portion of the rotor is not as tall as the ones that came off.
So when you go to put the caliper back on, the offset s wrong.

So what is the dimension of the height of the hat that sticks up from the face of the rotor surface for each year range of car?

The rotors that came off have "hat height" of ~63mm.
The new rotors have a "hat height" of ~53 mm.

Which one is right for a 71?

Maybe I have late spindles?

411-407-405 would be the right part # for early cars. 405B would be for 73 up. What is the part number on your struts? Something quick and easy to let you know is if you have 2 bleeder valves on your front calipers. If so, you have late front struts.

Also, if you have the wedge-pin type ball joints, you have later struts and so need later brakes and rotors.

--DD