New seatbelts can be had from either
SCHROTH - via Karas Engineering,
Frank Karas 856-629-0712 phone, or
frank@karasengineering.com
They quoted new inertial reel belts for mine after OSH, as I have two black, and two blue in my current plane.... You will need to send him dimensions, etc. Check out the website - nice belts.
The second alternative that I am aware of is:
AM-SAFE
My 73P has two of these in the front that were added to replace the originals: The existing belts are 1500 Lb Capacity, Am-Safe Belts Model 9600-22 P/N 502997-401-2251
I was getting quotes for (external) intertial reel replacements that allow you to bolt an inertial reel on the upper mount to make the seatbelts more user friendly...IE you can lean forward, without having to release/loosen the belt... With the current AM-SAFE's I either don't wear the shoulder harness, or have it loose enough, that it would do me little good in a crash situation... Inertial's allow you to 'move' but will lock up with any sudden movement.
Seems that the SCHROTH belts were about $350/seat...pricey, but not a bad investment..