Heater core / AC evaporator box

[PMT429]

I have a '84 GT and am working my way through the infamous heater core replacement. Since I have the dash off and have removed the entire heater core / AC evaporator box, I am giving it all a good clean. Those of you who have done this, do you "seal" all of the heater box joints with some type of silicone sealer? The shop manual I have does NOT call for this during assembly, but wanted to see if those with experience may have a thought either way. Thank you.

[wraithracing]

I generally use 3M strip caulk or 3M Windo Weld Butyl tape to seal up the HVAC unit. Both will stay soft and tacky for sealing the joints, but will be easier to separate at a later date than silicone or anything that hardens should you need to replace the heater core again. Good Luck!