I've been pretty confused lately about my 76' f250's 4 wheel drive. I have owned the truck for almost a year and never really gave the 4x4 much thought until i heard weird bindings noises when it was in it. The truck has warn hubs up front but has an np203. The shift in the cab looks like an NP205 handle on top (no lock positions) and doesnt have a 4x4 light like a different dent i have that also doesnt have locking hubs. For some reason I can only shift into 2 wheel drive and 4 wheel drive, just forward and back to two positions. I am wondering if i have some type of conversion kit the p.o. installed or what. I would like to get the clunking/binding noise straightened out and get it shifting right. Anybody heard of this before? i know the np203s have the chain which can make that noise.

 

You have the earlier Dana 21 single speed transfer case.

It runs 1:1. No 4HI or 4LO, just 2wd or 4wd.

 

i dunno.....it has the New Process factory tags on it, model 203 produced in 1976?

 

I would hunt for a good 205 and swap it out.

 

If you're sure it's a 203, then it has issues. It should go in 4HI, or 4wd LOCK. Same for 4LO. There is no 2wd mode in a 203, it's a full-time 4wd truck. Another possiblity is that someone installed a part-time 4wd kit on the truck hence the front hubs.

If you are hearing binding/whistling, the chain may need replacing from wear and tear.

 

Ya i have another 77 with the np203 and non locking hubs that works fine and shifts fine as well, i had been going along for months here thinking i had a 205 but these recent problems made me actually look. I think i'll just end up swapping in a 205 since i may already have one laying around. Is this swap a direct bolt on to my c-6 or will i have to change mounts etc?

 

Tail mounts are different.

 

My truck has the divorced t-case but the np205 that i think i have is not divorced. Does anyone know of an adaptor or what i should look for to make it work.

 

Since you have a divorced case, you will only need the brackets that are attached to the 205. You have a series of holes in your existing crossmember, and will accomodate the new transfer case. You will have to make sure that you have the driveline straight. Any compound angles (left to right) will create a vibration.
Anyway, you will find the set of holes that will work, and the 205 will go right in.
That being said, you will have to make driveline differences. Since the 203 and 205 are dimensionally different, you will need to modify the drivehshafts.

Lets talk about your 203. You cant get low range? I believe that you have a problem in the shifter. SInce you have one lever that has to perform two functions, it is common to find a shift lever that is not working properly. There is a gate that has a rod and spring that prevents the two linkages from being able to work at the same time. This rod can get dirty, and the detent can fail This will prevent proper operation.

For a quick verification. Remove the linkages from the case, and move the levers by hand. One lever is for 2wd and 4wd operation, and the other is for high range and low range.
Experiment a little, and drive it. Do this on the street with the front hubs in "free" so you do not bind anything, and you can determine whether or not you have a problem in the case.
Keep in mind that if your chain is bad, it is probably due to a lack of lubrication. If you have not placed your truck in 4wd at least every 200 road miles, or locked in the hubs in the same amount of miles, then you have ruind the case. See the 203 has a fluid reservoir that can only be filled with oil by the rotation of the chain. Since you have a converted case, the chain no longer spins if you are in 2wd. Without the rotation of the chain, the reservoir cant be replenished, and critical components cant get juice. This will bring a quick end to the case, and you can and will develop all sorts of noises.
The same is true if you run gear oil in the case. Lighter weight oil is a must here.

Regardless, it is a good case, though not too desireable. Since you have a 205, the swap is a simple one. You will have to make up some sort of mount for the 205 shifter though.

Twin stick is a quick and easy option at this point too.

 

I guess my 203 is converted too, I am not sure what is going on, but I am can tell you that I can put it in 2wd from under the truck and I have locking hubs, I have a 74 highboy, anyway, sorry for thread jacking and digging up an old post.---Jack

 

ya mine basically shifts 2 ways, 2 wheel drive and 4 wheel drive and thats it. I don't mind that really, but there is this horrible and loud clunking noise in 4x4 because i think the chain is gone inside. I think im finally going to buy a divorced 205 tomorrow and begin the swap.

 

Good luck with the swap and keep us posted!!