I have no idea on this but I have a 69 fj55 with no locking front hub. I just parted it out and the front axle throws me. It is always in 4 wheel. Was that normal. Sorry not to Hijack but that question brought up mine!
oh and my input is I would think a 73 but also not sure if that is a US model. Those mirrors throw me.
I've never seen mirrors mounted in that position on any pig here in the states. My 77 Aussie pig has mirrors on the doors but it does have moutning holes on the front fenders for mirrors. I'm guessing its 74 or earlier but can't say for certain.
And I believe up until disc brakes came standard (76 here in the states, right???) that none of the 55's came from the factory with manual locking/unlocking hubs. All of the earlier trucks I've seen have had either Warn or Selectro hubs or the drive hubs that keep the hubs engaged all the times. I believe all of those Warn and selectro hubs were either dealer or owner installed. My 77 Aussie pig has Warn hubs and a sticker on the driver door sill with directions on how and when to use them.
Every stock disc brake piggy I've seen has had Aisin hubs (grayish dials) and I belive they came from the factory like that. Gary S