knock knock?
 

I've got a very annoying knock on my '91' 80 sport. Seems to be engine related due to it knocking on start up and setting off/coming off throttle. All engine mounts seem ok and just wondered if anyone had any ideas where to look next?
Also, whats the big thick cable thing attatched to both sides of the bulkhead either side of the gearbox for?
Cheers, Phil .

That cable must be Procon Ten.

Whats that then? Is it some crash/impact type protection?