Only stupid question is one that don’t get asked
Glow plugs are used to heat up the cylinders in some diesel engines prior to cold starting. Basically the heat that ignites the diesel is from the compression of the air- cold winter days don’t always have enough thermal energy when the air is compressed to ignite the diesel.
Your Ford probably doesn’t have any because of its age. Older diesel engines typically used either an overfuelling button (more common on the bigger tractors), an intake heater (which was essentially a small flame that heated the air flowing through the intake), factory ether injection systems, or block heaters. I think block heaters are the best in most instances,
All a diesel engine needs to start is fuel, compression, and timing. Your injection pump will take care of fuel and timing both.
Before you jump into a full rebuild, get a service manual and check your compression and fuel to injectors. It takes a lot of hours to wear out a diesel. If it’s running rough, try some seafoam. I’ve had good results with it regarding cleaning fuel systems.
Also, if you’re new to diesels- you’re gonna see some really black oil. That doesn’t necessarily mean abuse- diesel engine oil turns black quickly compared to gas engine oil.
I’d definitely pay a little extra for diesel rated engine oil- these tractors have flat tappets/lifters and the zinc in the diesel oil really helps them.
I have a Ford 5000, she is a phenomenal tractor. You are welcome to DM or ping me with questions and I’ll do my best to answer.
Hope this helps.