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Tech Question
Lowell Grasse, Didsbury, AB, 1970, Plymouth, Satellite, 340
How Hard is it to put in an automatic tranmission with overdrive from a newer pick-up? I have 4:10 rear end, and a 4th gear would be nice.
We've covered this swap a few times over the years. Basically, the A-518 is a smallblock 727 with an overdrive grafted on. Early versions (1989 to around 1991-'92) used non-lockup converters that are 100% interchangeable with your stock 340 unit. The shift linkage, KD linkage, speedo cable, output spline, etc., are also the same.
Avoid the weak A-500 (based on the A-904.) The pans are the same shape as their 3-speed cousins and can be used for identification
You'll need to shorten the driveshaft and do some fabricating to get it to clear the transmission and torsion-bar crossmember. The stock Dodge truck mount is very tall, some extra room can be gained by using a biscuit-type Camaro or Mustang mount.
Somewhere around 1997 they went to electronic governors, you'll never get one of those to shift. Look for one with only the usual 3-pin backup-lamp and neutral safety connector and a two-pin shift connector. Simply apply 12 volts to the 2-pin connector and - voila! overdrive. Turn it off, normal 3-speed TorqueFlite.
One other consderation not to be overlooked: even though the cooler fiting are in the same place as you old 727, they are bigger (for 3/8" hardline). You MUST change your lines, and the cooler in the bottom tank of the radiator, to 3/8" stuff, or the trans will cook!
Great swap! One was in my daily driver 340 W-2 Duster for 7 years. It also had 4.10:1 cogs, flip the switch and - bingo - 2.85!
Rick
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