What is this?

[Big Camper]

I have this canister almost underneath the passenger seat of my 1979 CF LWB, it is wired into the loom (purple wire) and the alternator, it looks like an original part, but I cannot identify it off the wiring diagrams. I'm sure I sound really dumb with this but what is it?  See pic

[Jeff]

It looks like a relay. If the heavy wire goes to the starter motor, it's probably the starter relay.
My guess is that it is not a std part as the bolt/stud holding it up is far longer than it needs to be.

[LS120]

could be an external regulator... for the alternator   

[ben]

i dont recognise it.. follow the wires.. yeh i thats a good suggestion take a photo of the alternator for us so we can see if its a inbuilt reg alternator or not?
ben

[Hippo]

Could it be a solenoid used to charge second battery ?

Dennis (In NZ till 29th, Wellington and Hamilton)

[Warren]

Could it be a solenoid used to charge second battery ?

Dennis (In NZ till 29th, Wellington and Hamilton)

Thats my thoughts, a bettery isolator for charging dual batteries.

Warren

[Worzel]

Could it be a solenoid used to charge second battery ?

Dennis (In NZ till 29th, Wellington and Hamilton)

that would be my guess too,
but the solenoid could be used to isolate something else

[eddy]

disconnect the wire and see whats doesn't work 

[Kirk]

ITS A BOMB>>>>>>>>RUNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN!!!!!

[obsession]

hahaha