LHD? I wonder if it is a a conversion (I've never before seen pictures of nor heard of an LHD sunny truck).

I agree with Angelo, a small Datsun ute *probably* would not have been successsful in the US. The 521 and 620 trucks were derided by most of the population as too small and too cheap (though a large minority bought them and made them successful). What about other small utes? The Subaru Brat was successful, but arguably because it was four-wheel drive. The VW Rabbit/Golf pickup was less successful in the US, definitely a niche vehicle. Those were the last of the small utility coupes sold in the US.