Diamond tuck interior?

Howdy, I've got a black vinyl diamond-tuck interior in my 66'. It was installed back in the 70's and all the seats are absolutely perfect except the driver's seat. It has a big crack on the bottom and it needs to be replaced. Anyone know where I can get a new cover for it? I can't find one anywhere. I would just put in a whole new factory matching interior but I really like the look of the diamond-tuck and all the other seats look brand new (thanks to the years of being coated with silicone lubricant) any help with this? Thank, Later <><