Alright, so after tons and tons of time researching, and hundreds of hours of work, I can say that the automatic swap is almost complete. Yes this truck was a manual and is getting an automatic. Now because this is not a common thing to do, it’s pretty much impossible to find information on it. I decided that I will try to document my progress so far, and will add on to this as I finish the swap.



In the long list of large automotive projects, this one in all honesty doesn’t seem incredibly complicated. The important part is knowing that you have all the parts, and all the prep work is done before the transmission goes in.



the truck itself is a 95 with the 5.2, it came with the Nv3500 and Np231. So naturally when the case of the Nv3500 exploded and I needed a new transmission, the only one that was affordable and in good enough shape was 11 hours away. So after stressing for several weeks about what to do, I had the idea of putting an automatic in. I researched a ton before going through with this, but after getting confirmation that it should work just fine, and there were plenty of donor transmissions available, I decided to go through with it.



The donor transmission is a 46RH that came with another NP231. It came out of a 4x4 96 with the 5.2 so it’s a perfect match for my truck.



Now that I’ve gone through the story of the swap, I’ll try to make a list of all the parts you would need for this swap.



You’ll need the transmission (obviously)



Measure driveshafts, as the manual and automatic are different lengths so measure driveshafts and buy or cut or lengthen or whatever you have to do.



A shifter is also important to figure out. The automatics would have came with the column, so either get a column with the shifter from a donor vehicle, or get a floor shifter. I went with a floor shifter for the A727 from American Shifter, and with a little bit of modding the shifter and transmission case, it fits very well.



If you have a 4x4 you might need to get a new transfer case. I have read that the transfer cases attached to the manuals are slightly different than the auto transfer cases, but I cannot confirm or deny that. Do some research.



I also opted to buy an auxiliary trans cooler, you might not need one, but my truck has an aftermarket radiator with no spots to route the trans lines through it.



While on the topic of trans cooling, you should also check fittings and get cooler lines while you’re at it.



You will also need a TV cable, the 46RH requires it. I have not tested it first hand, but I have heard that driving without it will burn up the transmission lightning fast. Why risk it.



You will also need a flex plate. I believe the service manuals call them a drive plate. They are super cheap on rock auto, and with thin washers, the bolts that went with the flywheel will work with the flex plate.



Get a dipstick tube if you don’t have one. That’s pretty straightforward.



You’ll also need a bit of electrical. Depending on the 46RH, you maybe or may not have a torque converter lockup. Either way you’ll need to do some wiring, but it’s really not terrible.



You will also need a PCM, the manual PCMs will not work with the auto trans.



I also recommend using a pilot bearing puller, and a fluid pressure tester, I know there are methods to get around using the puller, but you should use the pressure tester on first start, just to be safe. The 46RH has lots of ports you can use to test pressure.



I would also recommend changing the filter in the trans.



I will update tomorrow with the steps I took to start the swap.

 

A 46RH out of a 96 truck??? Think I would verify its an RH before turning a wrench..... Should be a three pin connector going down into the top of the valve body part of the trans. If its an 8 pin, it's an RE. The RE started with OBDII trucks..... in 96...... Though we do have a member with a 96 4x4 with the RH trans.....

 

Yes it is an RH, I confirmed that when I went to pick it up, it might not have been the original trans out of the donor truck, but it is a fairly low mile unit.

 

Have fun pulling that auto out to rebuild it every few thousand miles.

 

The trans in my 96 was original, and had over 200K on it when I sold it. It still worked fine..... If they are taken care of, they last a good long time.

 

Maybe you had a unicorn, I know several people who had them always kept them maintained and they still failed prematurely, I have pulled several. They are very weak for a truck transmission, they can be built to be very good transmissions, but most people aren't willing to pay the price it takes to accomplish that.