I should add that I did not find Crutchfield's support to be that good - it required many calls before they figured out they had sent me the wrong relay connector. The way 'they' figured it out is when they sent me the wiring schematic and I realized I had the wrong connector. I did get a full refund on the part, though.

This does trsanlate into a waste of time and distrust of the vendor.

Eventually, I made my own relay connector by following the schematic and bench testing the whole thing with a 12v supply. All that bending over into the trunk/pump area gets really tedious....

I bought the third relay and socket for the horn and the diodes for the flashing lights (you only have to connect the rear ones to get all four flashing) at a local electronics shop. Very inexpensive.