Seems to be much closer to Derby testing than Preakness, with OOC testing and the like. Has been the demise of many a horse, some better than Chrome.
72 hour surveillance for Belmont, Met Mile, Manhattan and Odgen Phipps and all have OOC testing. All other stakes, horses must be on grounds by noon the day before.
http://gaming.ny.gov/pdf/05.21.14.BelmontStakesDay.pdf