Here are the relays I bought from the Ecology junkyard a couple weeks ago.
It looks like Nissan has used the same relays and relay holders for over the last 20 years. They're a modular design, which makes them excellent for retrofitting into other vehicles.
Here are the relays. Notice how they're color coded, and how the pins are nicely protected.
Here are the relays with their sockets; the sockets are also color coded. I don't know how to change the pins in them yet, but I'm very interested in figuring it out.
The sockets clip securely into these "ice cube trays"; then you insert the relays into the socket. As you can see, you can put whatever sockets you want in the tray. The trays are a pain to get apart, but the ones I dug out of the junkyard held up to the sun pretty well; they did come apart instead of just breaking. Once everything goes together, it's a pretty secure set-up.
I'm trying to figure out the difference between the blue/ grey and green/ brown relays, and what the amp ratings are of the different relays.