I had a 1980 "Bakkie" 4 speed with an A12 engine and it does need that 5th gear on the highway. A transmission from some B210, 120Y or 310 (60 series) will fit the A engines but you need to modify the reverse sensor and the rear support is about 2" further back.
I'm trying to import a Sunny pickup from Central America and the EPA requirements are not bad if it is older than 21 years but NHTSA must approve it before bringing it. I know there are several in the country.
Does anybody have any information about the importation of these cool little trucks?