so for heater core I found..
ACDELCO Part # 1560142 {#52481498, 88956887} $101.79
CORE,HTR

there also this one..
SPECTRA PREMIUM / COOLING DEPOT Part # 93016 {#98361} $37.79

Do I need any of these?
ACDELCO Part # 52478817
SEAL KIT,HTR NEEDED WHEN SERVICING HEATER CORE
or
SEAL,HTR INL & OTLT PIPE (O-RING)