I went digging about them for a while - there are some weird and
wonderful things out there loosely called taxis - the most amusing one
for moi was an attempt at a stretched beetle.
Also checkers tried a front wheel drive device which never hit production.
GM V6's aplenty in their lineage, it appears, too.

I can't get the idea about the Humbers outa here - and I note that no-one
I could find mentioned anything about the lineage of the Marathon other
than the A, B and other shite model numbers. So, were they chevs,
humbers, chryslers or what. i find it difficult to believe that a little
company building specialist vehicles came up (or could afford, since it
seems they were perpetually broke) with molds for the presses, or even
the presses. So, I reckon they were trucked in - bolt-holes and spare
metal added later:-)
It's eerily similar to the train buffs that know the model designations
of every loco ever built but don't have a fucken clue how they work, what
the design actually does and who 'invented' the various objects of their
obsession.
Or the plane spotters..... Hang on..at least they may have spotted some
'rendition' aircraft out here with their fixation with rego numbers and
'livery';-)

Faark - the Yankees sure as hell are    s  l  o  w   learners.

I recall I drove a 68 Falcon manual cab with bench seats, no seat-belts
and drum brakes.
With the bigger 6:-) It was almost 'expired' in the scheme of things at
the time, but it was in close to show-room condition - rare as rocking-
horse sh.t in the cab game then. Gear linkages were perfect and it had
real tyres on it, too. And wheel trims...
Speaking of slow learners, - it took me a few weeks to tell the owner of
the damm thing that as mechanically sound (not one rattle in it) as the
the thing was, he could stick it..

I loved the Shitney cabs with their light rail bumpers. Nice.

Shades of Citroen - did the Checkers cabs also get narrow track at the
back so girl drivers didn't stuff the tyres on kerb corners?
Duh - what am I saying - girlies driving cabs in Chicago and New York
back then?
Nah, not there.