Unfortunately, there is no reference to Old Jurong Road in the
1975 and 1981 street directories.
Anyway, in the 1972 street directory, Jurong West Avenue 2 (former
PIE) was known as Jurong Road.
The Jurong Road (parallel to current Jurong West Avenue 2) found in
1988 street directory is un-named in 1972. This, I assume was Old
Jurong Road. (Renamed to Jurong Road in 1988 when 1972 Jurong Road
was renamed PIE.
I know it's super confusing, so I will try to scan the map for
you.
Summary: Old Jurong Road of 1972 and 1975 (and probably 1977) is
probably 1988 Jurong Road.