[va_tlc]

well i had same thing, i rebuilt transmission, then like you a brand new driveshaft made and new slip yoke, still noisy, so took rear end cover off and jacked wheels up and found about 3 teeth off .. not a good start on this truck.
so orederd a new ring gear and pinon, also changed pinion yoke i guess ya call it, the one on ya rearend that holds the driveshaft. you may wanna check that mine was spread and the lil metal tabs that holds the u joint in place was wore about off. hope you have better luck than i did.