If you don't need 1 with the correct tag or serial #, then I have a completely rebuilt close ratio toploader that David Kee built for me. I live in the same town where he lives, San Antonio. (Lucky for me because I have all 4-spd cars)
I had this Trans in my 66 GT for a while (as its orig unit was being rebuilt) and had him fully rebuild it for my 69 Boss a couple years ago. In the mean time, I found a #s matching one (tag) while imy 69 sat in the body shop...
As RadBoss mentioned, he offers virtually everything new, used, or improved... and never cuts corners. On this one, the tail shaft is his casting (DKT) which has 2 improvements over the OEM Ford unit; venting as many racers added and the later style rear support (side-by-side vs inline font->back). This mounting design employs a different rubber/rear insulator that Ford used after '71 or so and on many A/Ts. I was going to use 'poly' mounts ( on engine mounts too) as the side-side one is the only 1 available like that which I could find. This is why I went with this tail shaft.
I think i have $1800 in this one. (memory fades) To get one like it will cost you $2k, easy... You can have it for $1500 + ship. I'll dig up the receipt if interested and get you a copy &/or pics. I even have a cool trans container for shipping that can be used if you return it afterward.
The main case is OEM Ford and has the orig serial # stamped into it from 67 or 68 and the tag (RUG-G) says it was from a 390 GT Mustang. So this is a fully functional, ready to bolt-in Boss 302 equivalent... There will be no problems nor will there be any excuses. It will perform like the 'bullet-proof' 4-speed that Ford over-engineered it to be. (The 390 input shaft is slightly different than the 302 and so it was also replaced during the rebuild.)
Let me know,