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I had a np-208 slip yoke in my 1986 f150. I called and bought a used np208 from a salvage yard but once I got it I found out it is a fixed yoke even though i told them I need a slip and now I'm stuck with it . I don't have the money now to buy a new driveline and no one around has a used one for me to buy. I'm wondering if I can just swap the outputs on the 2 transfercases. ( I know I should of just rebuilt it or gone other routes but this is where I'm at now) I've posted elsewhere and just gotten lots of nasty comments about how stupid I am and that Google has all my answers I can't find anything . I'm just looking for a straight answer on if it will work or not I don't know much about t-cases. Thanks in advance
You would be taking apart the "new" transfer case you got, and using the good parts from it to repair your original transfer case that has the proper output. Don't see why that would not work as long as the bad pieces were not on the output of the old transfer case since you definitely cannot use those pieces on the original setup. Have I done this before? No.
Can you simply unbolt the output and slip the other output pieces in place? I am looking at some of the teardown instructions and I would say no. It looks like a large portion of the transfer case needs to be taken apart to remove the output shaft and swap it out.
Sorry, I can't help with the details of swapping the output housing. In theory, it should work but I don't know about any internal differences that could cause issues.
This makes me wonder what was wrong with your original transfer case? If not destroyed, it might be easier to repair or rebuild that unit. You'd avoid running into potential mismatch problems when combining two units. I've rebuild several similar chain drive transfer cases. It's been a while, but I don't remember any problems. They are generally quite simple. Unless worked hard extensively in 4WD, the chain and sprockets last forever and usually don't need to be replaced. Typically all you need is new bearings and seals and some other minor parts. Oh anyways, just a thought that might save some grief.
One word of warning: Whether you do a rebuild or just swap parts, do NOT use RTV sealant. Use an anaerobic sealant for the case:
The problem with RTV is the little rubbery worms that get squeezed out. They will break off and clog the oil passage to the bearing on the input shaft. These units have a very basic oil pump that moves oil to this bearing. It's not really much of a pump, more like a spiral disc that ever so gently persuades oil to move in that direction. It doesn't take much to block this flow, and the "pump" barely creates any pressure to overcome any restriction. I've seen a couple of chain drive units destroyed due to the use of RTV. The bearing starved for oil and seized in the case.
I'm tearing the old one apart now and one mount is broken off and the case has water in it. I live in alaska so 4wd is used most of the year. I'm going to try and swap as much internals as I can but I'm not far enough in it now to see what exactly broke. My output tail is fine still
As Frank Zappa would have said, "Yowza! Yowza! Yowza!!
How did that damage happen? That's pretty nasty.
Towards the bottom right of your picture, see that trough cast into the housing? It continues in the other case half. IIRC, that's what carries oil to the front bearing. Maybe I'm getting my models mixed up, and the NP208 may use an oil slinger instead of a pseudo-pump. The slinger throws oil everywhere, and some runs down into the trough and eventually to the front bearing. Unfortunately, RTV shards will eventually collect there, too. So please forgive me if I'm getting my models mixed up, but after seeing that pic, I do remember having to pick RTV pieces out of that trough.
