So, My grandson just bought his first truck. He has an 89 Dakota with a 3.9 and the auto overdrive trans. Reverse is out of the original trans, and I have a good auto overdrive trans out of a 91 Dakota with 3.9 under my bench, that's been there about a year.

Other then the trans cooler lines on the 91 being larger then the trans cooler lines on the 89, is there any other issues I might run into? If the trans cooler lines are the only issue, we will add the larger lines, and probably go with an aftermarket cooler hung in front of the rad.

So, what else is going to be an issue? Gene

Check to be sure they both have the same od and governor wiring plug in.

The plug appears to be the same. The shift and kick down linkage connections appear to be the same. The driveshaft output is the same, the speedometer connection is the same. Both measure the same length. We grew concerned when we saw the trans cooler lines on the 91 were so much larger then the 89, and all action stopped.

The raised numbers on the bell housings are different, I assumed it was because of the different years.

Will the torque converter to flywheel pattern be the same?

I don't have the time or space to do this, so my brother in law is performing the trans swap, along with other things. He is a good backyard mechanic but was concerned about the line differences, and he says he is only doing this once. Gene

should go right in without big problems,both sound like A500 TRANSES,check the bellhousing to see if it has a cutout for a crank position sensor,tho i thin k that started with 92 trucks

91 will have the magnum flex plate/converter and have the cut out for the crank sensor... these will need replaced/ swapped out...

If it is just reverse is out, you may want to look to see if the one way clutch is bad. if that is the case it may not be hard/difficult/costly to fix..

Rodhall,
The 91 trans I have does not have the cut out for the crank sensor and the converter looks a lot like any of the regular newer 904 converters.

The story on the Dakota when we bought it, was that reverse has not been working for 5 or more years. On top of that, the overdrive wires were disconnected, and it had a pretty delayed 1-2 and 2-3 up shift (which could have been an adjustment issue), but I did drive it 15 miles home. We will keep it around for a builder trans, because I wouldn't want to trust anything less then a full rebuild on this one. Especially with a new teenage driver.

If the 91 trans wouldn't have worked, we would have went ahead and rebuilt the 89 trans. Gene

magnum v6 with crank sensor cut outs started in 1992