69 Charger A/C Box Installation Question

[69RTSE]

Putting my restored A/C box back in the charger.  There are 5 metal washers and 5 foam washers that are used in the installation.  Do the metal washers go against the firewall or against the A/C box.  Thanks.

[tan top]

foam washers go between the inside of the firewall & thick washer on the heater box studs ,
so slide washer on first then foam washer

[440]

I often wondered about those thick metal washers... What purpose do they serve ?

[tan top]

I often wondered about those thick metal washers... What purpose do they serve ?

just to add strength to the firewall i think    !!    the weight of a fully assembled A/C heater box is really heavy !   if you bolted the box up with out these & being the fire wall is so thin ,i'm sure  there would be movement if you were to try to rock it ( also vibration over time , could stress crack the  firewall maybe), so with the nuts on the out side having a fixed washer to them sameish size  as the thick washer on the inside !!  by the time its all bolted up , its not going anywhere !

thats my guess 

can't  comment on a non A/C  box