New to these truck

Wish mine was like that . I think mines had a tough life. Was originally blue for what I can tell under the bonnet . Seat isn’t for that truck I don’t think . I’m not sure what the seats from . Doesn’t bolt in that’s for sure 

Whatever colour's on the firewall is usually the original colour.
There's no magnet inside the generator, they have a wound field which is powered through the regulator when you turn the ignition on. The regulator usually just needs the points cleaned. It's not too hard to hook the generator up as a motor. If it motors, it'll generate. Lube the bushing as John said and check that the brushes aren't stuck.

Jarrod.

Look at some YouTube clips to clean n test a generator. Bronze bush at the rear gets a drink of oil. Bearing up front can also have a small drink. Remove the brushes n armature. Use some wet n dry to polished the commentator then replace the brushes if more than half worn. Buy at any auto electric shop. I had to file down some brushes once for a starter motor that was rare n that works well. 
from memory there is very little magnetism in a generator so well worth the try. YouTube will show you how to test it on the bench to make sure it works. Some people don't like generators n prefer to fit an alternator, I'm not one as the original system works perfectly well when both generator n regulator are working.

You can loosely date a vehicle by the codes in the (British & Aus) makers logo etched into the safety glass. Take some close up pics and post them here and will have a go at deciphering. Assumption is that glass manufacture and truck build might be within 3 - 12 months of each other.

Further to Mammoth's reply, there will also be dates on the starter, generator and likely other electrical components.

Jarrod.

Just remembered about identifying the colour; there "may" be a long thin tag in the engine bay starting with "BERG", or "BALM". If there is, post what it says. This is the colour tag. Can't remember if Inters had it, or just Dodges.

Jarrod.

Looks like it may have been dark green ...and IMHO good chance its ex army ...........the 1950s army road vehicles were painted a gloss dark bottle green ,not the olive drab of later army stuff.

Does anyone know what the pcd is in the al160 truck 5 stud and insert dia 

I notice your truck has a 2 speed diff.  I am wondering if this was an upgrade at some time, as if it were factory i would expect the spec plate to say AL162.

As far as i am aware 160 designated single speed diff, which were common with the Australian Army.  I think the possibility of your truck being ex army has been mentioned previously, although the army spec trucks usually had towing loops bolted through the top and bottom of the front bumper, at the front of each chassis rail, which i don't recall seeing on your truck.

I just thought it was worth mentioning, to perhaps assist with tracking down a more definite origin.

Brett.