According to Autozone, my truck, '93 Z71 4X4 5

According to Autozone, my truck, '93 Z71 4x4 5.7L, is supposed to have a "Starter Solenoid" of some kind mounted on the firewall or fenderwell. "Plus" the solenoid on the starter itself. Like the way Fords are setup. They say it helps eliminates hard shifting, improves mileage, etc. Well, my truck is a Frankenstein. I bought it like this. Spaghetti wires & all. Not the original motor. My truck does get HORRIBLE mileage, & when it grabs 2nd gear it'll give you whiplash. It came with an electric shift kit for towing made by B&M. Throw the switch, it makes the time between shifts longer. My question is, where is this alleged, 2nd starter solenoid supposed to be located? I have no such item anywhere on my truck inside or out. I have attached a photo of the solenoid. Thank you.