Thanks for the suggestion Tim. Before I started taking the pan off I tried locking two nuts onto it but no luck. THey were no match for a pair of vice grips though.
The new no1 tensioner is the same in function, but totally different in design and geometry. The ratchets are the same spacing, but the new tensioner extends about 3-4mm further than the old one.
I sure hope this sucker fixes my rattle otherwise tools will be thrown ;-)
For those interested, have a look .....