Saginaw transmission mystery --- could be 1970-'75 Camaro / Firebird - $130 (West Hills)

I always thought this transmission came out of a 1979 Mercury Capri but I think it may be a Saginaw 3-spd transmission out of a 1970-'75 Camaro.
You be the judge (and please let me know if you know otherwise): Photo 3 of 9: GM 3952645 4 F209 Photo 5: 3860042 GM 10 Photo 6: GM31 8925647 109 Photo 9: I can't make out the numbers/letters too well.
.
.
may be: CV3 3920710 Please let me know what this is and what it came off of if you know.
$125 COMMENT SECTION: "Hi there, Saginaw 3 spd with 1st gear syncro.
These are good units" --- Johnny