How is the 1HDT engine block grounded?

[finderscuba]

How is the engine block grounded wrt to negative posts of the batteries?
What would happen if the engine was not grounded? What wouldn't work properly? Glow plugs? Sensors? Fuel cut solenoid? Alternator?

 

[Dougal]

There's usually a big-arse earth strap.
Without it, your starter will earth through all the other little wires and probably kill everything they're attached to.

 

[70sguy]

Neg post of both batteries are bolted to the engine block.
Also a smaller ground lead tied into ground cables at the clamp, go to 10mm bolt on inner fender.