The seat belts have arrived. The default attachments have big holes, and the cabin lap belt attachments are AN4 hardware. The solution is to drill a proper 1/4" hole in the metal attachments. The crotch strap gets AN5 sized holes. I wish I had predrilled those holes before I put the seat pans down. I'll have to buy a stubby 5/16" threaded shank bit for my angle drill. There is not much room down there to use a regular drill bit. The shoulder harnesses connect to a cable that goes back to the longerons. The attachment for the clevis on the cable will require using the standard hole. I fabricated some AN4 sized spacers to fit inside of the big hole on the belt attachments. I put 6 AN4 washers on a bolt, then spun the bolt and washers on the drill press and filed the washers down to fit.