Assuming everything is as advertised I'm going to buy a '98 Mountaineer with 121k miles and body damage tomorrow. 5.0L engine is the main reason but now I'm thinking about keeping the 4R70w behind it. It would be nice to have overdrive since I'm currently running the stock 3-speed manual and with 4.88s and 35s it is tapped out at about 60-65 MPH.

A couple of issues with keeping the Mountaineer tranny are the expense of the adapter and the need for shorter driveshafts. Just extra $$$ but I don't want to drop a bunch on this since it started out completely unexpected. I have seen where some folks have had success with the ZF adapter on an AWD 4r70w but there is an issue with a seal that I haven't figured out yet. That would save a fair amount on the adapter and shorten the power train by ~4.5". And of course, I'll have to figure out a new crossmember and shifter but I'm not too worried about that.

I have a fuel pump in the basement and will have to run new lines. Get the ECU up to Garry to get rid of the security key stuff and whatever else (second bank of O2 sensors probably)... Figure out which way to go with the cooling - new radiator or crossover hoses.

I kind of dig the manual tranny but the 3-speed isn't the long term answer and I'm not necessarily opposed to an automatic. The newer, more reliable power train certainly holds some allure as well.

What am I not thinking of? Hopefully nothing too important but I can still change directions at this point.

Great timing. I'm starting down the same path. I posted a thread that had a list of everything I could think of. I'm staying with my NP435 and will be selling the 4r70w that came with mine.

Will be great to compare notes with you.

Adam

Again, perfect timing. We're about to pick up the AOD adapter for the 4R70W in the club truck. We mulled over the ZF adapter hoping to save some coin on the build, but the uncertainty of the ZF adapter mod/seal requirements led us to believe a proven solution would be the better option.

With the 4R70W or AOD OD gear ratio you may find yourself wanting 5.13 gears with 35's.

With a ZF5 4.88's work out right, but there is more overdrive in the autos.

Be interested to see how these all pan out. I'm interested in doing the same combo some time soon.

And so it begins...

You'll love the 4r70w.

If for some reason you don't choose to use it, I would be interested it buying it

Just to throw another option out there. I'm told the NP205 will bolt directly to the AWD 4R70W, no adapter needed. I'm sure you need to fab a cross member and change drive line lengths. But, it may be a stronger, cheaper option. I think NP205s are still a dime a dozen. However low range is not as low as the D20.

I looked into the np205 and it seems people want more for them than I'm willing to pay. Most of the ones on CL are like $300. For that price, I'll pay the extra to have the Dana 20. Maybe I'm just cheap. :-) I don't know what you can get one for at the yard though.

Did those of you runnning this combo keep the VSS? It looks like the sensor is in the tailshaft housing which will be replaced the the AA kit. The only option I'm aware of is the new sensor that attaches to the D20 and combines the VSS signal with a cable driven speedo. At least one of the vendors sells them but it sounds like a lot of folks don't run one.

4R70W has it's own output shaft speed sensor. It doesn't need VSS in addition to that.

I run mine successfully without the VSS.

I reprogram the PCM to use the OSS instead of the VSS.

The only situation where you would need the VSS is if you were NOT running the 4R70w and wanted to keep EGR or Evap.