Only the left side manifold is different.
Check with Dan Augustine (Oso) as he's been collecting numbers of '89 Specific parts
1988 Mighty Max turbo 2.6 service body
1980 Power Wagon W400
Sundry Mitsubishi Montero Gen 1 parts
Parts vehicles: 1980 D50 2wd, 1988 Mighty Max 4wd, 89 LS Montero 4-door, 2002 Sport AWD
For Sale: 1989 Power Ram 50 extended cab