I am reluctant to disagree but I bought a 1968 B18 out of a 142 that had the
dual downpipe exhaust manifold and the aluminum dual carb intake manifold.
The block appeared to be B20 but was clearly marked B18 with cast letters on
the left front. My guess is that the last B18s were made using the later
design castings that became the early B20s. The lot of parts came with a bunch
of half-washers which appeared to be factory-made also and I was slow in
figuring out what they were for till I installed the manifolds. I am not sure
of this but the car MAY have been delivered in Panamá.
--
George Downs Bartlesville, Heart of the USA!