As of May 13, 2021, the AAR has issued the following update to Rules 88 and 108 of the Field Manual:

Any freight car requiring permanent general repairs in excess of the hour limitations of Rule 108 (36 hours including trucks or 25 hours excluding trucks) must have all truck mounted brake cylinders on the car reconditioned per manufacturer specifications. Purging and cleaning do not apply toward labor hours.

Download the circular here.