Glow plug relay is near to the brake master cylinder - well on that side of the car in the engine bay. Some cars have relays for extras such as AC in the engine bay too - more standard stuff like the emergency blinkers and the rear window heater relay are under the dash on the left hand side of the car.
Dont forget fuses, vacuum Ts, valves and lines, unions etc. Special screws, nuts, connectors, and anything else you can sneak into your pocket LOL! (Not condoning stealing, just being funny) But in all seriousness Ive been saved alot by those little bits that are unavailable today or cost more to ship than it actually costs.
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