The date code is present on all GM product castings and forgings, clear
back to at least the 1950's. They might make a part identical for several
years, but the date code changes frequently. "P.I.T.A. Purists that restore
GM vehicles want everything exactly period correct. That goes to things
like windshield glass, fasteners, headlights, you name it. Such is the
state of the art on the show circuit. My last show car, a 1961 Cadillac
small roof 2 door hardtop DeVille, was judged in a number of national
concours shows, got points knocked off for replacement headlamps.
Picky, picky, picky. Never enjoyed that part of the show circuit. Every
time we drove it to an event, I hovered next to it like an expectant
father. Takes some of the enjoyment out of it, for sure.
So, your manifold easily could have been made later than the coach,
but be identical in every respect. Functions exactly the same. Don't spend
another second thinking about stuff like that. Drive it with your family,
make some lasting memories, have a great time in it. My take on it, anyhow.
But, if your coach is one of the only Five (5 ea.) Coca-Cola/Pepsi
comparison challenge contest prize coaches, you are going to want period
correct, all numbers matching components from bumper to bumper. They are
the only significant GMC's ever made, and clones abound. Just like the
EM-50 from the movie Stripes.
Jim Hupy
Salem, Oregon
On Tue, Oct 22, 2019, 4:13 AM Rich Kinas via Gmclist <
> Ok Interesting...I'll take a picture of both tonight and post so we can all
> take a look and see if we can figure it out. I'm going to put them back on,
> I just like to know all the ins and outs of my coach.
>
> Rich
>
> On Mon, Oct 21, 2019 at 7:02 PM Richard Denney via Gmclist <
>
> > The two manifolds are pretty different in any case because the left one
> has
> > to work around the transmission.
> >
> > Rick “not thinking they changed over the years” Denney
> >
> > On Mon, Oct 21, 2019 at 5:51 PM Rich Kinas via Gmclist <
> >
> > > So I finally got both my manifolds off (no broken bolts). Yipee! Got
> them
> > > both sand blasted (no cracks), osphod and painted with 2000 deg flat
> > black
> > > paint. Interesting drivers is a 76 manifold and passengers is a 73.
> > > Although they have the same shape, (Mr. obvious speaking) they do look
> > quite
> > > different. Are there any specific reasons one would be concerned in
> > > running this configuration, two different year exhaust manifolds? I
> sure
> > > cant
> > > think of any, just thought I would ask, just to be sure.
> > >
> > >
> > > Obviously the passenger manifold bit the dust some time in the past.
> > > Interesting also is that the front bolt for the passenger was larger,
> > must
> > > have
> > > broken in the past, drilled out and tapped to a larger bolt size. I
> doubt
> > > this was original. So getting all the surfaces cleaned up then going to
> > > check for flatness. More rain this afternoon in Orlando, which keeps
> > > interrupting my progress.
> > >
> > > Rich
> > > --
> > > Rich Kinas
> > > 1976 Elaganza II
> > > Orlando, FL
> > >
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> > >
> > --
> > '73 X-Glacier 230 "Jaws"
> > Northern Virginia
> > Offlist email: rick at rickdenney dot com
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