I did mine one wire at a time about 9 years ago using a 10 position terminal board and 5 relays with fuses. Very happy except if I had it to do over I would have put both the terminal board and the relays high on the engine side of the firewall where I could reach them instead of up under the dash where my fat 75 year old 6'5" tall body doesn't want to go anymore.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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