Roof Gas Strut help please

[DB-1584]

Has anyone knowledge of the different styles of side elevating poptops?
My recenty acquired '81 needs new gas struts and I'm struggling to know what to get.
It's not a Devon or a Leisuredrive, has one strut at either end but may need two?
It's the same as the one in the link below, anyone got one or know who made it so I can get some struts?

http://forum.club8090.co.uk/viewtopic.php?p=7751035" onclick="window.open(this.href);return false;