A/C Install, The quest for coolness begins Options

[jPs]

I know most of y'all take A/C out of your 914's but I'm hoping to add it and am wondering if anyone can give a little advice.

I just aquired an old underdash unit manufactured by Heatransfer out of San Antonio, TX. I've read that VPC and DPT made underdash unit and so this might be a little unique...I dunno. At any rate the underdash unit appears to have everything needed such as expansion valve, standard pcar looking blower motor, etc. From the unit runs a red line (12v hot), green (ground), and red (compressor relay). Bench test shows that everything appears to work correctly and I also have picked up the original York compressor and a relay of some sort with the unit but I've no clue how it's to be wired or what. Below is a picture of the connectors and the only info on the relay is 150-10 12V.

Forgive my ignorance here but first does anybody know what the relay pinning is or is it even really necessary to run a relay. From what I can figure I should be able to connect (red) compress relay line direct to the compressor and evaporator fan and I'm guessing the underdash unit would trigger the compressor and evaporator fan to kick in as needed....am I off base here or do I need a go-between relay some where in this picture?

I have access to R12 and evac machine on the cheap and so I may upgrade the compressor down the road based on performance but for right now I'd like to get it all hooked up and see how it runs to begin with.....any advice would be GREATLY appreciated. I am willing to buy a new relay but admittedly I'm clueless on what I would need.