Rear seat belts—which way?

[69 Rustang]

I was starting to assemble the rear of the interior tonight…finally!  I ran into a problem though.  Which way do the rear seat belts install?  Does the button mechanism go to the outside or mount in the center of the car?  It seems like it would be better if they were mounted with the button part on the outside in case it gets stuck between the panel and the seat cushion, it would be easier to get back out or less likely to even happen.  But, tell me, how do they mount?  Thanks!

 

[timachone]

They are mounted in the center of the car, buttonside up. 

 

[1973 Mach-1]

They are mounted in the center of the car, buttonside up.

Yes they are, as mine disappeared down the rabbit hole in the seat crease, and are a bear to either fish back out, or remove the seat to reset.