I just drove down to georgia and it is beginning to get hot. decided to try and fill the refridgerant in my r134 converted 82 300d. i have only recently moved to the south and never cared for air conditioning until now so i know little about the system. the can of refridgerant says to make sure you put it in the lower fill fitting not the upper, however it seems there is only one obvious place to charge it, ie a fitting right on top, directly behind the radiator. there seems to be no other fitting, at least in plain view ( i'm sure ther is a discharge fitting, i just havent bothered to locate it.). My question is,: is this fitting in plain sight right on top the correct place to fcharge it up? And also, without a gauge, how much to put in? any help would be great. driving around in humid geogia heat with a two year old is driving me nuts!!