First, I want to give credit to Sonoraed (not sure if he's on this site -- maybe just the other one) for the idea. He tried and seems to be the first to post a finished product. He claimed to me he got the idea from somebody else. Anyway, I don't claim credit for discovering that this works.
Second, sorry for the poor write up. I wasn't really thinking about documenting it, and failed to get really good pictures as I was doing it. This is my best attempt to reconstruct the build with all of the details...
So we all know how pathetic Chrysler's attempt at the 89-91 wiper motors was. The problem has been that working motors are non-existent, and if you could find a working one chances are it won't be working for long. We need a suitable replacement that is easy to source, easy to install, and works in the confines of the tiny space in the tailgate where the original motor sat.
The Durango has a suitable replacement. I know 100% that the motors from 1998-2000 will swap in perfectly. The motors will work from 2001-2003 as well, but there is a possible catch: I have seen some of the motors from these years missing the small black control box -- suggesting the continuous/pulse/park function is handled elsewhere in the vehicle's electronics. You need a motor with the "black box." More on that in a second.
You need to pull EVERYTHING off the donor vehicle. Just make sure the arm, mounting nut and all of the spacers/covers/gaskets are there before you start. If you are missing any of the components just look for another donor vehicle -- this is super easy to make work if you have everything, but probably not workable without some significant fabrication effort if you do not...
From the outside, pull the arm, dish-shaped spacer underneath the arm, and the motor mounting nut. As opposed to the mounting nut on the 89-91 GWs, you will not
snap off the motor housing when you remove the mounting nut, so feel free to use a little elbow grease if needed to get it off. Then carefully pry/pop off the outer half of the tailgate gasket. You should now have everything off the outside of the vehicle. Here are some pictures of what you need to get. The wiper arm (and the little plastic trim piece/grommet) is not shown.
Then go inside the tailgate, and remove the large, cheap plastic trim panel. It is held on with a couple of screws and some trim panel grommets. The wiper motor will be right there, held on by two 10mm bolts. Pull the motor, making sure you get the inner tailgate gasket when you take the motor out of the tailgate
. I cannot stress how important this one little piece is/will be. You might need to pry at it a bit, or go back outside and push it back through the hole. Just get it. Now trace the 4 wire harness past the plug, and get as much of it as you can. Cut it back at least 8-10" if possible. You'll now have both sides of the harness -- the part attached to the control box (black box) and a good length of it on the other side of the plug as well.
You'll now have all of the parts you need for the swap. Here is a picture of the motor you are looking for:
Now the mount for the motor needs to come off. Pull the two bolts mounting it to the motor, and pry off the little cable stay that is attached to the harness. The control box is also attached to the mount, and needs to come off. It 'clicks' into the mount and is held there by a little tab, but I couldn't get anything thin enough to push in there to try and release it. I just gently (but firmly) pried it off of the mount with a large flathead screwdriver at the point noted.
Now for the fun part -- cutting on your perfect tailgate. There's no way around this -- nobody is ever going to reproduce that original wiper motor, and nothing else on the planet will work and fit in that small hole. You have to make the decision now -- busted motor (or an empty hole, if the motor is gone) or perfect, working motor that will require a little fabrication. There's no going back after this!
Picked up the step drill bit at Harbor Freight. It looks to go from 1/4" to 1 3/8". You need to drill to the 1" size and then STOP. Check the fit of the inner tailgate gasket. If the little rim does not fit snugly through the hole (mine didn't), go one more step
to 1 1/8" and check again. You want the inner rim of the gasket to just pop through the hole in the tailgate. It shouldn't be distorted (forced through), but you don't want a gap, either. Go slow and check frequently.
Now the motor goes in clocked differently than the original. The original was clocked at exactly 6 o'clock. The new motor sits at about 8 o'clock. As you sit in the back of your GW, looking up through the access panel hole, the left side of the Durango wiper motor gear box will clip the reinforcing channel to the left of the hole in the tailgate by about 3/4 of an inch. This will prevent the motor from sitting flush against the inside of the tailgate. This reinforcing channel needs to be trimmed back to allow the motor to go in. Credit to Sonoraed for the following picture, which shows exactly where you need to trim (angle grinder, sawzall, plasma torch, whatever works for you). You just need to take off the little tab shown in the photo. Go slow -- it's much easier to remove more than it is to put it back!
Once you have the fitment all sorted out, you have one final decision to make. You can either cut the pigtail off the original motor (if you still have it), or cut the plug off the harness in the tailgate. Either way you need to splice the GW tailgate wiring to the Durango motor. Each has four wires, and each wire has a corresponding location on the new motor.
There might be some different wire colors, but just remember: red/yellow seems to be universal on the GW harness for +12V, and black is ground. On the Durango, pink is universally +12V, and black is ground. The other two wires are continuous wipe and pulse wipe (for the washer). You might need to test to make sure you don't get these backwards.
I opted to cut the plug off the tailgate harness, as I think in the future if I need to swap in another Durango motor I can do so quickly; it will literally be plug-and-play at that point.
Now get everything test fit and snug up the motor mount nut (outside the tailgate) and make sure everything is seated and flush. Then you need to add a strap/brace between the motor and the tailgate. I re-used the mounting bolt on both the motor side and the GW side -- mounting the tailgate side of the strap to the bolt hole that originally held the OEM motor. Once the Durango motor is in place you will notice that the bolt holes for the motor and the tailgate mount are not in the same plane. I used a 90 degree 2X4 nailing brace from Lowe's/Home Depot -- carefully bending it until it was flush with the motor case and the original tailgate mount. I then re-used the 10mm motor mount bolt on the Durango motor side, and the original GW bolt for the tailgate mount. You can see from my installed pic that the strap is perpendicular to the axis of the motor rotation, so there won't/can't be any rotational movement of the motor. It is in there really solid.
Here is a pic from the outside -- You can see from the years of built up grime around the old bezel that the new mount fits nicely in the area where the old one occupied!
Sonoraed's finished product as well. He did his a little different -- IIRC he was missing the inner/outer Durango seals (remember how I said those were very important to get!) and had to make a spacer for it to fit. His arm needs to be clocked down a little:
Only conceivable downside is that the Durango arm is about an inch longer than the stock 89-91 GW, so you can't use a 13" blade as before. I have an 11" on there now, but it looks like a 12" might clear the top of the glass as well. It wipes a great pattern as-is. Another member here (Babywag) grafted the arm of the GW wiper arm to the base of the Durango wiper arm. This gives you the right length and the right angle. I just used the entire Durango arm, and mine is clocked correctly (it sits flat on the tailgate rubber seal), it's just a bit longer than the hybrid arm, and requires a bit shorter wiper blade. You decide.