Having (successfully, I might add) just grafted an OD onto my '73, I
have the following comments to add to the thread.
1. You have to get an OD/tranny combo. The output shaft differs from
the non-OD tranny and the surgery is not worth it. For a 73, you need
the 4-synchro tranny with an LH OD.
2. If you have the right tranny/OD (vide supra) the driveshaft that
is on the car will work. The legends about different driveshafts
apply to the earlier (3-synchro, type D) lashups.
3. IF you have the correct OD for a 73 (Black label, with a 1972
somewhere in the series number) the speedo you have will work. It
will read about 1% fast (and you will get about 1% better gas mileage,
or at least you will think so). That level of inaccuracy happens from
a couple pounds difference in tire pressure, so I wouldn't worry about
it. If you have a BLUE label OD, you will need a speedometer from a
later car.
4. The wiring for your OD is already in place. However, since the
switch has not been used for 22 years, it probably has some crud on
the contacts. You will probably have to pull the wiper/OD switch from
the steering column and buff the contacts with fine (600) paper.
5. Aforesaid wire comes out in a bundle near the "anti-run-on"
valve/bodge. It is yellow, and will probably have a one-wire Lucas
bullet connector socket on it. This will be full of road residue and
should probably be replaced. You will have to add a wire in the
harness that heads down toward the reversing switch that is on the
tranny. You should see 12v on this line when the ignition is on and the OD
switch is on.
6. This wire should feed through the 3/4 gear lockout switch, which
is on the left side of the shift extension. This should be used, it
is there for a reason. The itty bitty gears in the planetary of the
OD cannot take the torque of the lower gears, and you will shred your
nice new OD if you use it with lower gears. No, you cannot rely on
your memory to turn off the OD when necessary.
7. You will also need a new speedo cable. You may use your original
right-angle drive. Someone once said that the cable is long enough to
do away with the right angle drive, but I don't see how, since the
cable attaches to a point that is bounded on three sides by the
driveshaft tunnel, the OD and a frame cross member.
8. Put both the wiring and the speedo on the unit _before_ slipping
the unit all the way in and bolting up the rear cross member. Once
it is installed, you _cannot_ get to this stuff.
You will find that the OD drops your RPM about 500 at cruising speeds,
which turns interstates into a pleasure instead of a busy buzzing
droning tedium.
Good luck! A. B. Bonds
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