Hey guys n gals, had this shock absorber taken off of my g40. It has the same at all four corners. The reason it was removed is because the cap that holds it in was missing. The original cap (pictured) does not fit, this means i had to replace with a standard shock. Obviously this isnt ideal and i would like to put the large shock back in. 

I know it is blistein in make. And i think it is ‘b6’ variant. But i am unable to track down a cap for one. Blistein arnt returning my emails despite asking me for part numbers etc.

Can anyone help?

This is the part number from the larger shock.