Totally different seat from the TR3A.
The seats are 'handed' and the straighter side goes towards the tunnel.
I made my own straps from webbing obtained at a local fabric store. I
still had the old straps so I reused the hooks, made the straps a bit
on the short side then they were very taut when stretched into
Moss (and likely others) list a seat webbing kit (p/n 681-330) no idea
exactly what it includes.
Suggested annual donation $11.47