The Fuji serial numbers of that format were in use from 1975 to 1979.

In the serial numbers that I have seen there have been four different digits in that position: '0', '1', '5', '9'.

I have seen the Gran Tourer model serial numbers with each of these four digits in the fourth position of the serial number.

I have seen the America model with the '0' and '5'.

My sample size is not large, but I cannot see any pattern as yet.