I'm not criticizing Joe!

it looks like the a/c and heater lines moved some as well as the size/shape change of the blower motor hole.
I'd like to see a 72 A/C firewall to figure out when the change occured(72 or 73). It appears they are the same 67(?) up to 71 at least and 73-76 were the same.
Did the change occur in 72 or 73 is what I'd like to know