84 is actually the wrong year. I always think this truck is an 84 but it's an 82 or 83. Anyways, I was at my parents yesterday and was going to take the aux battery setup off this truck and I noticed it had a piece of metal none of my other trucks have over the hvac box. It appears to just provide another point for the dryer to hook to. At first I thought maybe the early evaps didn't have two points of attachment but I checked the diagrams in my 80, 83, 85, and 86 books and they all look the same.
All I can think now is that it helps prevent the dryer hoses from pulling down too much? Not really sure that's a problem though.
It may be more common than I know - can't say the hvac box is where my eyes usually look when opening the hood of a truck.
Edit: I guess it's an accumulator rather than a dryer - havent delved into a/c much yet...
Scott
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Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole
But there ain't nothin' wrong with the radio