On the Dana 44 differential TTB in my Bronco it clearly says "44" embossed in the metal (on the bottom of the differential between differential and transfer case). (My van has a Dana 60 straight axle.)
Go here and read about your engine:
http://www.ford-trucks.com/forums/forum48/
I am not sure that I would want an E350 with a 5.4L. My 1/2 ton Bronco is a 5.8L and I wouldn't want to go smaller. But there are those on the SportsMobileForum.com that own or have owned 1 ton E350's with 5.4L engines. I would ask them. And remember mpg is not based on engine size (otherwise we would all be running 1L engines) it is based on the mass you need to push - pure and simple. If you are pushing 9,000 lbs. up a hill it will take approximately the same amount of energy (i.e., gasoline) whether the engine is a 5.4L or a 5.8L or a V-10.* The exception is a vehicle with alot of forward gears to limit rpms to the precise number necessary to sustain movement up that hill. (I lied, mpg actually equals rpm, but nevermind for this example.) That is why the new Jeep Cherokee comes with 9 gears and the Dodge Sprinter has more forward gears than an E350. *An economics example is Milton Freidman who stated that "The real rate of taxation is equal to government spending.")
Here's a list of things re choosing a 4x4 van from the full size van subforum:
http://www.ford-trucks.com/forums/searc ... d=10864249
Read the entire thread:
http://www.ford-trucks.com/forums/10000 ... van-2.html
and then you might want to pm this jcee guy:
jcee
Senior User
2000 Ford E-Series Van
Join Date: Jun 2008
Location: Erie, Pennsylvania
Posts: 168
Hey, hold out for the 4x4. I have a 2000 Ford Quigley, 3/4 ton, 5.4 triton and I'll tell you what. Once you have a 4x4 van there's is no comparison. I'm in N/W Pennsylvania, right on Lake Erie and the snow and ice here can be unbelievable. The 4x4 van handles it with ease. Granted, you're hauling around some hefty extra weight with the solid axle front, transfer case and bracketry, and the mileage ain't the greatest but it's worth it in capability. You can do all you want with a 2wd to try to get you in there and back out but in the long run the 4x4 van beats all. I run highway speeds on 35's and have no problems. On the Quigley everything is Ford original except for the Quigley bracketry and their technical and support department will provide everything you need. Whenever you need it. "IF" you need it.
Check Quigleys site, Ebay and just google 4x4 van and go from there. You won't regret it.
As far as the 4x4 goes, in my experience, you can tell alot about it by locking the hubs, putting the transfer case in 4x4 and listening to how things lock up (or don't) driving it 6 feet and then putting it in reverse and driving it back 6 feet. Then taking the transfer case out of 4x4, then unlocking the hubs. Did the hubs lock and unlock easily? What did you hear driving? After being taken out of 4x4, does the front drive line still spin when the vehicles moves forward or back? If not, one or more of the hubs is not disengaging.
I like UJoint's motto: "Do it nice or do it twice."
I am redoing mine because it was not initially done "nice" in my opinion.
The Borg Warner BW1356 transfer case has a known leakage problem out the tail piece. That will need to be fixed if you are leaking fluids. In fact it would be good to check what level the fluid is. Google it.
My BW1356 leaked so much and I didn't stay on top of checking it that even after a rebuild it slips out of gear - that means out of gear, freewheeling - while going downhill when I take my foot off the gas. Not good. Because to put the transfer case back into gear you have to be stopped.
The BW1356 transfer case on my current 1995 Bronco works flawlessly and my bought new previous 1993 Bronco was working flawlessly when I sold it at about 200k.
But in a diesel 7.3L van, in my personal opinion, the BW1356 transfer case is a little too weak. Others with more knowledge may disagree. In your case, for a 5.4L gasser, it is probably fine. I hope UJoint or Baja or others will chime in here.
Probably the most important thing to ask the owner, who obviously knows the faults of the vehicle more than you could ever tell in an hour of checking, is "why are you selling it?" "What are its problems?" Listen carefully, because most people will tell you, but the will not place the emphasis where it should be. So, ask about each problem and ask for the seller to demonstrate the problem for you.
Because I really don't know much, and my personal opinions are generally different than most peoples', take my advice with a big grain of salt.
I will tell you this. Your van was not made as a 4x4. So you will have to treat it delicately. And you must get to know it and its peculiarities. It did not have the millions of design dollars put into the 4x4 drive train like the F-series trucks did.
That said, there are few more satisfying vehicles than a SMB van or SMB-like van with 4x4.