Hello Richard
Thank you for your reply.
I don't know what the cable is lined with. It is a standard MMC handbrake cable for the post 1993 rear brakes. If anyone knows, I would be interested to find out.
The sealant between the gearbox/propshaft covers and the floor/chassis frame, which I scraped off, gave the appearance of being window frame sealant. This is readily available, retains some flexibility and is cheap. The Hodgson non-drying bedding sealant sounds appropriate, from the description online:
https://mystatic.co.uk/seamseal-cv-white-sealant . The Tiger seal is more expensive and might be "too" sticky, making future disassembly difficult? I'm probably just overthinking this!!!
David Stuart