lowering springs for an 86 GT

[bob at cemetery.homeunix.org (Andrew Basterfield)]

Hi

I'm looking for some lowing springs for my 86 GT (UK) and I thought I
could fit any VW A1 springs, but many spring manufacturers specify
different parts for different models, eg:

http://www.eurocarparts.com/ecommerce/Response.asp?action=SEARCH&type=PRODUCT&part=937440041&item=1

http://www.eurocarparts.com/ecommerce/Response.asp?action=SEARCH&type=PRODUCT&part=937440141&item=2

Also a Boge 40mm set I am looking at is only marked as suitable for Golf
mk1 and Jetta mk1

What are the differences between the A1 springs?

--Andrew