There are lots of them here in NZ, I'm not sure but probably more than half of the 60's here are JDM - probably nearly all of them high roof with glass sunroof.
I had the glass of mine one fine day disconnecting from the steel underside / frame. The glue just went soft and let go. Purchased a whole sunroof assembly some years ago quite alright priced at approx $130 us.
They have gone up in price since here too, but I believe that you could easily get one. The shipping will be harsh I would think.
The supporting steel frame tends to get rusty too, you must check that before buying...
Cool locking truck by the way. A well dialed in 12HT is a somewhat permanent pure smile producing machine....
Also check this - years ago I posted that one
While searching for some water ingress I came around these nice kinks in the front sunroof drains.
They are located on each side behind the plastic panel to the left or right of your shoes. Both sides similar kinked. Have a look on your one !
They were not the cause for the flooding - but good too fix it anyway. Just put some 13 mm hose connectors into the tubes.
The flooding was caused by an blocked lh side drain in the cave behind the bonnet hinge. Quite good accessible after demounting the hinge.
Cheers
All the best from down under....
(Forgot temporaliry how to quote)