360 taillight wiring pigtail ?

I am installing a modified 360 challenge rear grill and taillights into a very modified Lancia Montecarlo. Looking for some help w/ the wiring. The 360 taillight housings have a oval electrical socket w/ 4 pins. Does the entire chassis wiring harness plug into them or is there a shorter wiring harness that does. Looking at a parts diagram, looks like the 3rd brake light does have a separate short harness, but doesn't show taillight wiring. Would like to have the proper pigtail/socket to snap into taillights but don't know if I can buy a short new harness from dealer or if I need to look for a salvage car to cut the chassis wiring harness.

 

Thanks. That'd work fine if I hack off the connector to the 360 wiring harness and splice into the Lancia. But I called the dealerships and Ricambi and they are $300 and I need two. That is more than a set of 4 taillights cost new.

So I research more and looks like 360, 550, 575M, F355, F512M and F50 all share the same taillights. Looking at the 575M wiring diagram, ref# 13

http://www.ricambiamerica.com/parts_catalogs.php?M=FE&P=&V=diag&I=1156

looks like a wiring harness for both lights per side and are only $22.69 each. Wonder why the huge price discrepancy for just one connector difference. Any ideas?