The retractors are '66-'67 Deluxe Seat Belt retractors.
The seatbelts themselves are standard '65-'66 Standard Seat belts.
Your first picture DSCN0045.jpg tells the whole story.
From top to bottom, Here is what you have:
Belt#1 (Very top) looks like a short Front center male belt from a full size car. (NOT used in a Mustang) - Do not use.
Belt#2 (2nd down from top) - Male Front standard seat belt. Bolts to left or right front Rocker Panel.
Belt#3 (3rd down from top) - Male Front standard seat belt. Bolts to left or right front Rocker Panel.
Belt#4 (4th Down from top) - Female Rear standard seat belt with buckle. Bolts to left or right center wall behind Rear Seat next to trans tunnel.
Belt#5 (5th Down from top) - Female Rear standard seat belt with buckle. Bolts to left or right center wall behind Rear Seat next to trans tunnel.
Belt#6 (6th Down from top) - Female Front standard seat belt. Bolts to left or right side of Front Trans tunnel right behind bucket seats.
Belt#7 (7th Down from top- Very bottom) - Female Front standard seat belt. Bolts to left or right side of Front Trans tunnel right behind bucket seats.
You almost have a full set for a '65-'66 Mustang, but not quite. You are missing both of the Rear seat Male outer belts. Each of these belts gets bolted to a nut housing on each of the inner rear wheel well braces. You might try hunting on Ebay for the missing rear outer belts. They come up often. The anchors for the rear Seat Belt Male belts should be identical to belt#4 and belt#5. On early and mid '65 cars, the rear seat belts were optional, so there is no provision for rear seat belts behind the rear seat, but you can add them if the provisions for them are not there.
Again, The retractors are '66-'67 Deluxe Seat Belt retractors, and CANNOT be used with these Standard seat belts. They are meant for '66-'67 Deluxe Belts only, so you can hang onto them if you ever run into a set of Deluxe belts the same color or dump them on ebay. They are used only in coupes or fastbacks, and will not fit in convertibles.
Hope this helps!
Any questions?
Tony K.