How to tell what speedometer v3, v4, v5, v6
 

Hi guys and gal's

Just a question as to how to tell what version a speedo is from?

Is there a part number or serial number?

Is there any way to tell, I don't have a car to plug it into, it does not have dccd? As the v3 facelift/v4/v5/V6 sti all look the same?
As the early v1/v2/v3 are totally different this is no problem.

Version 4 facelift

Version 5 or 6


Thanks for any help