sstine9,
IMHO I wouldn't bother spending any extra money for the Sanden plate if it doesn't come with the 505 compressor. If this the same one I got with my 505, I ended up cutting it to pieces to make it fit. It will also depend on which aftermarket A/C you have (VPC or DPD). I ended up getting a combination of parts from both systems.
My notes were not where I expected, so I'll keep digging for those, but below is the wiring diagram. There are two sources of 12v. power from the AC unit. One directly from the positive on the battery. The diagram doesn't show it but you really need to put an in-line 25-30 amp fuse here. The switched power comes from the #9 fuse (4th from the right end of the panel). The ground also runs to the engine bay. I tied mine into the ground bolt just underneath the relay board. You should get all the electricals hooked up and tested before proceeding to have the system charged. If any problems occur they can be addressed before the system is full of freon - which is costly to replace.
I have some spare parts, since I'm not putting A/C in the second car, and you can have whats left for very reasonable price (if you need them).
Enjoy!
__________________
Gerard
74-914 White - Soon to be a custom 3.2L Six

87-924S 2.5L Artic White - SOLD

74-914 2.0L Ravenna Green - SOLD