Ive never seen a autech model with a helical lsd fitted, never seen one with a H on the end of the trans code, and only a vauge reference on a japanese site that it was a factory available option. Its possible that some people ticked the helical lsd option, and the cars were fitted but the build plates left stock.
There doesnt seem to be any difference between autech/sedan/wagon, same specs all round, but the autech ones we are seeing a lot of all seem to be the driving school cars.