Anyone know how to take apart a deluxe seat belt buckle?

Got a beautiful set of deluxe seat belt buckles but for the life of me I cannot figure out how to take them apart to rethread the belt through.

Any help or hints would be appreciated.

Kinda hard to do it yourself...but its possible if you do it REALLY lightly and gently with a thin, flat screwdriver.....otherwise I'd send it off if you want them 'restored'.

Stinking 73 LT Camaro (well, all 73 Camaros) have year only unique buckles and they were made poorly so the faces pop off alot.....finding good ones are hard enough ;)