heater core disassembly of heater core cabinet? on 1990 Chevrolet G Series Van (G10)

trying to replace the heater core, but don't know how to get the cabinet apart,
does it unbolt from both inside under the dash and outside through the firewall?

Asked by for the 1990 Chevrolet G Series Van (G10)
1 answer
Did you ever find an answer? I need to do the same in a 91. Thanks.