I liked my AOD, but the application was totally different and the AOD assembly that I had for my '68 never got installed. I prefer an auto for a large displacement engine in a 4x4, not so much for a small displacement engine.
Allow me to be a little less clear.
The AOD is mechanically modulated. As with all mechanical autos, it's shift schedule is determined by a set of competing inputs. The output shaft governor is a centrifugal device that provides a variable pressure signal to the valve body in proportion to output shaft speed.
The valve body must schedule the shift points based on engine RPM, engine load, driver demand, and road speed. Guess what. Those pieces of information are not provided to the transmission.
The transmission has a series of hydraulic channels that must be pressurized in order to select a gear ratio. So the valve body has the unfortunate task of scheduling the upshift, And it has to do that while the idiot operator is commanding various demands. If you shift to soon, it's a slug. If you shift too late, the engine screams. If you shift too fast, it's a jolt. If you shift too slow, it's a marshmallow.
But how does the valve body (mechanical brain) know what the operator wants, and what the engine is doing? Enter the vacuum modulator. The modulator was an ingenious device that could inform the valve body of load on the engine. Coupled with a demand over-ride device, (kick-down linkage) the valve body could successfully schedule upshifts to meet "normal" driving conditions and be tuned to function. This technique worked from 1950 to the mid 90's. So 40 years of evolution and success. If the engine vacuum is low, delay the shift. If the engine vacuum is high, schedule the shift. If you point an old 3 speed down hill, and let it idle in "D" it will coast, and shift itself into 3rd at about 20 MPH. Same transmission at WOT on the freeway, and the 2-3 upshift happens at 70 MPH. The entire schedule is interpreted by knowing the engine load and demand. And manifold vacuum gives a reasonable analog variable representation of that. But engine vacuum is finicky, and vacuum modulators require service and maintenence. Fast forward to 1980, and the re-introduction of the throttle valve. But with a twist. The throttle valve did not simply provide an analog pressure between two setpoints. It provided a full scale pressure based on "throttle position" and with no position input at all...it commanded zero pressure. So disconnecting the throttle valve cable (or installing it as a WOT kickdown) initiated the self-destruct sequence. Furthermore, the TV pressure output is "tuned" to match the somewhat linear engine load approximation of a 4bbl carburetor primary butterfly...which is TOTALLY different than the engine load experienced on a single giant EFI throttle body butterfly. It is a very sensitive, and precise, and the most important input signal to the transmission. And it is almost NEVER calibrated and tuned correctly, except by the factory...sometimes.
This scenario worked, (or didn't work...) from 1980 to about 1991...when the automotive world figured out that a computer could be installed with the transmission, and scheduling could be performed electronically. And the world changed. (...but It did make a Billionaire out of Anthony A. Martino, the founder of AAMCO.) Once the electronic scheduling started, and once the solenoids improved, automatic transmission were changed (and improved) forever.
So IF you are a competent auto enthusiast, AND you carefully calibrate your Throttle valve to your engine load, (or clone someone else's) then you have a chance of getting your AOD to schedule properly. Then you only need to perform the mechanical upgrades to the internals to get it to survive. But it's even better if you add a computer. Ford did this for you in the 1996 Explorer 5.0. They call it a 4R70W, but it's really an AOD-E with all the upgrades and a new name. ( And of course GM and the 700-R4 had to be renamed 4L60E.)
So either pony up and put a durable 6HP26 in it, or run the manual.
