Tannon Weber’s guide to identifying and exchanging TorqueFlite automatic transmissions
Important: contributions from Allpar readers are leading Tannon to make revisions to this page. Any input you may have would be appreciated via our change form. There may still be imprecise or incorrect statements on this page.
The following might prove useful to people looking for information on their RWD Torqueflite transmissions. It applies to Chrysler application transmissions, but may not apply to Torqueflites that were sold to AMC or other OEMs.
A-727 transmissions from their inception until 1966 have 19 splines on the input shaft. Non-lockup 727 transmissions from 1967 onward have 24 splines. Lockup 727 transmissions that debuted in 1978 had 23 splines.
Not all 727 transmissions made after 1978 were lockup; towing package 727 transmissions commonly were non-lockup, and would have the ’67-onward 24 spline input shaft. The A-518 overdrive also has 23 splines. The output shaft has 29 splines.
A-904 transmissions from their inception until 1967 have 18 splines in the input shaft. Non-lockup transmissions from 1968 have 27 splines.
Lockup 904 transmissions appeared in 1978, and have 26 splines. A-500 overdrive transmissions also have 26 splines. The output shaft has 25 splines.
If in doubt, count the splines. It saves a lot of headache and stress later on when you might otherwise discover that you have the wrong torque converter or drive shaft yoke.
The 904 and 727 don't have a common dust shield. The 904 uses a 10.75" converter. The 727 used either a 10.75" or an 11.75" converter, so the bell housing is larger at the bottom and deeper at both the top and the bottom. The starter ring gear is also larger.
The starter itself mounts in a slightly different position as well, so things like headers might work on one and not work on the other. If you're converting from a 904 to a 727, at the time this was written the dealer carried 727 dust shields for around $25.
For small blocks, 360 engines and some 318 engines of the LA family are externally balanced. They use specific balance weights on the torque converter, and are not the same between the 318 and the 360. The 340 engines in 1972 and 1973 used cast cranks, and thus used their own unique externally-balanced torque converters also. (Allan)
The 5.9 Magnum engines are also externally balanced, but don't use the same balance weights as their pre-Magnum counterpart, so torque converters from the late seventies and eighties 360 will hook up but not balance properly on the Magnum motors. For big blocks, the 400 is externally balanced as well, so it should have its own particular set of balance weights.
Rick Ehrenberg wrote: “All 318 (5.2l) engines - Magnum, SMPI, or carbureted - are internally balanced, therefore there are no torque-converter / flex plate swap problems.”