Nick, hang out here for a while: http://www.aircondition.com/wwwboard/
The high side Schrader valve is on the driver side of the condensor; the low side Schrader valve is on the inboard side of the driver side wheel well. The above referenced site is a wealth of MVAC info.
The Golden Rule
1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)