It's not the original distributor that came in the vehicle, they were vacuum retard. The advancer suggests it's an earlier F engine distributor, but there are quite a few other features to consider. First, the breaker plate is the type used on later non-US distributors and other non-Land Cruiser Toyota distributors. Second, there are no small holes where the early metal ID tag was attached to the distributor housing. Third, there is no oiler cup provision on the side of the housing. Fourth, the distributor cap clamp adjacent to the advancer body wasn't used on the earlier F engine distributors. Fifth, the wire clip under the advancer mounting screw wasn't used on the F distributors with a replacement advancer.
My guess is that it's a non-US distributor that's had its advancer replaced at some time in the past. It could even be an aftermarket Century (made in Japan)
F engine distributor.
BTW, the breaker plate stationary plates is installed 180 degrees off.