
Update. Joy has returned. The Mini adapter came and I fitted it tonight and now no leak. Unfortunately I didn't see your comment about the UNC shorter bolts in time but I reduced the long ones by cutting out the middle bit of the studs and welding them back and with two 12mm nuts as spacers and a TEMPORARY job was achieved whilst I await proper bolts for the job.( I am impatient).
With regards to the old Purolator, I have added a picture of how I assembled it. I blocked the inlet, put an airline to the outlet, immersed it in water and bubbles came out, so I think despite it looking ok it was faulty. Anyway I now have a simpler task of changing filters.
One minor point, the filter in the link didn't fit the housing. I ended up with a Mahle OC 21 filter which has a 3/4"-16UNF-2b thread. Anyone no what the 2b means. Just in case someone else follows this approach for changing the filter housing.
Also I haven't use the metal pipe but gone rubber as I found. Any comments as to whats best.
Thanks for all the help.