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?

Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
1 answer
Did you ever find an answer? I need to do the same in a 91. Thanks.