The only 'overdrive' transmission I would consider putting behind the 3.9 is the 4 speed manual that was offered in the late 70's -- the A833

That one sounds pretty cool and with the loss of the parasitic load of the TC and "slushes", it just might be OK...

it also has a great first gear
Overdrive (mid-1970s and newer)3.09 1.67 1.00 0.73

this, in reality, is the only one that would work IMO..

http://www.allpar.com/mopar/transmis...ed-manual.html

anyone want to donate to me -- Ill be the guinne pig LOL

 

I don't know that this will bolt up to the magnum. I have converted automatic cars to manual four speeds and its no picnic, but was worth it. I think you are on the right track. At least with a manual you can immediately tell the engine lugging and drop a gear.

Truth be told: even with a 5.2L and 46RE OD, the manual says to you are to disengage the OD when hauling max load on hills or pulling heavy trailers that seem to be lugging the motor. If you want the full load carrying capacity you want the 5.9, but I just don't appreciate that fulltime -2 mpg hit when my van is loaded less than 1% of the time.

I get 12 - 13mpg running up to the store and back, and 18 on extended hwy runs at 75mph, and frankly I can live with that. Screw gas milage: owning a reliable 1/2 ton truck that seats 7 -8 with still lots of excess cargo capacity beats owning a minivan or a Sprinter van IMO.

 

Well I can't seem to find another three speed so it's either rebuild or swap. I got this V6 thinking it would be good on gas and I can't break 11mpg. And that's highway at 55-65.

 

IMO I would rebuild the 3 speed.

In my cartest simulator, the gas mileage around down actually DROPS with the 4 speed auto in it around town, probably because if its higher first gear. On the highway it is only 1.5MPG increase. Top speed is only achieved in 3rd, so this kind of says 4th can and is a little too much for the van. Also having a larger OD tranny behind the 3.9 can have these issues:
1: the OD tranny has a larger TC, long input/output shaft and just about larger everything. You will use at least 5 HP more to just turn the transmission.
2. The higher heat content in OD will shorten the life of everything in the van...the trans, the PCM, the water pump etc. etc. We all know how much our vans like heat.
3. Lugging a motor is really not that good for the main bearings...

I really think the only one you can use is the manual OD.

I actually love the A999/32RH. I had it upgraded, rebuilt and reinstalled for $900 with tax! You will not find another auto that is this inexpensive. The A999 has NO electronics and is actually very tough. The Wrangler crowd prefers this transmission when rock crawling or running out in the back country. It really has its place. If you give yours up, you will probably never get one back

As for the gas mileage, you really have to have these vans running in tip top shape. When I first got my 3.9 I was only getting 10. After a new tranny, new NTK o2 sensors, a new cat, and tune up I am at 12-13. I get 14 on the highway. With the 10-15% ethanol crap gas that is out there, along with the FL heat, that is the best I am going to get...

 

this is the right attitude when owning a van LOL

 

Yea I'm going to try and rebuild it myself this winter. Until then I will just take it easy and get parts ordered. Any upgrades I want to take care of while I'm in there?

I put 50 miles on my buddys full size ford van with a v6 and got 16mpg. What the heck!? And that has the E4OD.

 

Pretty much: its a 7' x 7' rolling billboard that weights about 3 tons.

Lowing it 4" might help, and a spoiler that scrapes every driveway and speedbump might help. Chopping the top another 3 or 4" might help. I think in the end though most of these mods are going to get you a max of 2 mpg improved highway milage and the headaches probably won't be worth it.

It is what it is.

If you drive enough miles that saving 3 to 4 mpg is critical, then just get a minivan. They are cheap and available everywhere. They have 1/2 the power and less than half the cargo capacity but they are a better option for many people. You'll save some money on gas but you'd be surprised how little. The average compact car with 4 cylinders only gets 16 - 18 city and 24 - 26 highway.

I blame E10. My rolling wreck '79 Mustang that I built specially for rural delivery was a highly modified (rebuilt 2L OHC Capri engine, modified to a 4 speed manual) With a completely gutted interior (just the dashboard and 1 seat) I used to get 20 city and 30 - 34 mpg highway in the early '90s.

 

Yea I'm going to get rid of this van as soon as I am done fixing it. Goining back to a SOC Saturn with the 1.9l. I used to get 41mpg hwy with my 1991 SL1. Only had higher output coils for better spark on that. I think the station wagon will be a good work and vaca vehicle.