Correct OEM S/C Belt or Gatorback Replacement

Does anyone know the current model number for an OEM (GM) S/C drive belt for a 1999 GTP (stock pulley). Also, is 4060660 the correct Gatorback replacement for the stock pulley? Apparently, the numbers have changed and each dealer wants to supply a different belt.

That's the correct Gatorback for a 3.25" to 3.8" pulley. Stock GM s/c belt pn is 12574914.

Thanks, that helps a bunch!!