There should be ID marks on the belt. They would show length, width plus any other relevant dimensions. Have a look on the flat area, hopefully still visible
There are no markings on the belt, just wear & tear!
If it helps, the toothed V belt on my '93 plus8 is a Gates 6224MC.
This seems hopeful Jads, I'll get one off EBAY and compare it to mine, thanks.