Yes......several forum members are using them in 65-66's.  BB has them in his coupe, and t has them in his FB...  use the seat tracks from the original seats and bolt them in.

Do you need to use stock (vintage) seat tracts to fit them ('68 or '69 Mustang).  Thanks, Kim

Just keep stock seat track frames measure your floor mounting holes or the old seat holes where the frame mount double check mark these measurements on the new seat. Then check measurements again then try and use a piece of metal underneath the seat frame against the foam on the new seat this way when you drill and the bit goes threw the seat frame it doesn't go threw the seat foam to possibly going threw upholstery yikes. After all this is done use four 7/16" bolts if I remember correctly with the nuts and washers and mount the frame to the new seat and check fitment. The only thing I forgot to mention is I'd check seat fitment first if you attempt to use a different seat as the seat maybe wider and you may have to off set where the seat frame needs to be drilled