Thu Aug 19 21:00:10 1999
From: Michael B

Brazzadog aolcom writes:

>> The latest bit of confusion is this:  The tranny shop says I don't have
a BOP TH400 between the 360 and Dana 20 in my '71 Wagoneer.  They say since
it has a round top then it cannot be a BOP TH400.  I had thought that BOP
TH400s and a 2" adapter were used until '74 or so when the TH400 was
re-cased for the AMC motors.  I can see what looks like a 2" adapter
between my 360 and TH400 so I've assumed (bad, I know) that it was the
stock BOP TH400.  So... if it's not a stock BOP TH400, what is it?
<<

Ben, There was a lot of demand for the TH-400 by other automotive
companies back in the '60s. So GM made a TH-400 case which was 2" shorter
than the regular GM TH-400 case and was designed from the beginning to use
a 2" adapter plate. Then each company could machine a 2" thick adapter to
mate it to their own engines. They called it the Universal TH-400. It won't
fit anything without an adapter since the front case pattern is unique.

Jeep, Jaguar, Rolls Royce, etc. used the Universal TH-400. And they all
made adapters for their engines.

Around '72, Jeep's production was rising under AMC's wing to the point
that designing and producing a case for the TH-400 with an integral AMC
bell housing bolt pattern became feasible. The cost of time req'd to screw
the Universal TH-400s to the adapters and then to the engines exceeded the
cost of developing the integral TH-400 case. And you know if the auto
manufacturers figured they could save 2 cents per unit, they would.

Jeep made 3 different adapter rings for the Universal TH-400. AMC 327,
Buick 350 and finally the one you have; the AMC 304/360. The Buick 350 is a
BOP pattern engine. I'm not certain if the Buick Nailhead used the BOP
pattern as well or not?. The Nailheads were last produced about '66.

BOP stands for Buick, Olds and Pontiac. Cadillac also used the BOP
pattern, but for some reason they were left out of the acronym.


"Ken Wetherall"  writes:

>> were these round top non-cadillac th400s used in other makes??? or is
this type just a massed produced version so the end user wood simply make
an adaptor to mate this 'universal' th400 to their engine???
<<

Ken explained the same thing I did above already i see. Except he did it
in Ken Speak and I can only read Ken speak. Can't write it :-).


 -- Michael Baxter,
 From Reno, NV USA on 19-Aug-1999