Will it did 550 husqvarna

Yes this will fit your 550 along with these other powerheads :

Electric 16, 40, 42, 44, 45, 49, 50, 51, 55, 55 Rancher, 154, 234, 238, 240, 242, 242XP, 246, 254,
254XP, 257, 261, 262, 262XP, 335, 336, 338XPT, 339XP, 340, 345, 346XP, 346XP E-TECH, 346GP, 346XPG, 350, 351,
353, 353 E-TECH, 353G E-TECH, 357XP, 357XPG, 359, 359 E-TECH, 362, 362XP, 435, 435E, 440E, 444, 445, 445E, 450,
450E, 455, 455E RANCHER, 455 RANCHER, 460, 460 RANCHER, T540, 543XP, 545, 550XP, 550XPG, 555, 560XP,
560XPG