Rimmer's have a good guide here:
https://rimmerbros.com/content--name...le-Information
But I'm not sure that all types are still available and prices for OEM are higher than other suppliers. Just before Christmas EuroCarParts had a sale on front springs (Anschler) I bought two pairs for our "fleet", think they were about £8 each! Now the price is £56. CarParts4Less (their cheaper sister company) are worth checking. Depends if you want original or accept aftermarket, don't really think it makes much difference as long as you fit in pairs. I went to the trouble a couple of years ago of buying Swedish Lesjöfors springs in the hope they'd last - one broke after two years (got a refund after a six month wait).
Regards