I have a 1977 fulltime 4wd F150 and want to make it a parttime 4wd. I know the NP203 has a kit to make it part time but I would like to go with a NP205. I have a NP205 in my 78 bronco. Everything is the same on drivetrains, so it should swap right. I have not seen a swap like this on the internet or 4wd mags. All I find is the kit for the NP203. My NP203 is stuck in low and I do not want to take it out. Last time I tried to take it out, it never got it back in a gear. I spent some money on a rebuild. I probably need another rebuild anyway bacuase the chain is popping when I put a load on the drivetrain. Any Help!

 

You are on the right track, getting rid of the 203 is really the way to go.
A couple of things are, or should be discussed before you go tearing into this deal.
You indicate a 77 truck, and also indicate using a Bronco for parts, or at least as a donor.
If you actually have an early 77, then you will have a divorced case, and the married or direct mount transfer case will nor work.
If you have a late 77 truck (77.5) and this truck does have a married or direct mount case, just like the Bronco then all will be fine.
Adapters will interchange, and so will the crossmembers. Remove all of the applicable parts from the Bronco and botl them to your truck. Simple as that.
You will require the shifter, and so forth. Keep in mind that the rear driveshaft will not work in this application. The 203 has a much longer output than the 205 so the driveshafts are different lengths. Front driveshafts are also different, but the Bronco shaft will work under the 77 truck as long as the transfer case interchanges. Thats the married, divorced thing.
As long as both cases are of the married, or direct mount, then you will have no problems.

 

When you talk about divorced/married, what would I be looking for. I have the truck at the ranch, so I will have to go and look. I'll be buying the NP205, sold the bronco.

 

A married transfer case is bolted right up to an adapter that attaches the case directly to the back of the transmission.

A divorced transfer case or remote mount will not be attached directly to the transmission, and will have a small driveshaft that sits between the transmission and the transfer case.

The case out of the bronco will be a direct mount since this was the only configuration available, but depending upon the year of your truck, it could be a divorced case.
Count the driveshafts under the truck, and if you find three, and the case is in the moddle of the truck, then you have a divorced case. That being said the case from the Bronco will not work.

 

Holy smokes!!!! I have made a terrible mistake.
Read again, I messed up and have sent you on a wild goos chase!!!

You have an F150! This is identical to the 78/9 bronco and everything that i was saying about the divorced case is incorrect for an F150.
I dont know why I read that you were working on an F250, but I have made an error.
Your cases will be interchangeable.

Rear driveshafts are not a driect replacement, but the front is.
My apologies for information that was inaccurate.

 

Good! I guess I can put front lock out hubs on the front end and will be good to go.

 

I've read over this interchange before, but it might be worth asking in this thread. What was the original reason for the NP203 (chain) style married case on the 1/2 ton trucks anyway? I can understand eliminating the additional drive shaft but why something weaker in it's place? Was the addition of a full time based setup (203) just that much more promising over a divorced setup for the lighter duty trucks for some reason? I can't stand the parasitic loss of the 203 even when in "N'. Installing lock out's doesn't help much unless you tend to reverting back to being engaged for lubrication to keep from parts failure.

Purely learning here....

 

I tried to do the swap from one of my bronco's to the other one....THE TRANSMISSIONS ARE DIFFERENT!!!! I had to swap the C6/203 for the C6/205...I originally tried to swap just the T-case....It HITS THE CROSSMEMBER!!! the 203 Version of the C6 is shorter!!! I was able to just swap Trans and T-case from the Bronco with the 205 into the bronco with the 203...and had the front and rear drivelines to swap as well...so it was a bolt in swap....BEWARE!!! Drive line issues!!

 

I think 75F350 said there was a kit for the transmission. Maybe a longer adapter from tranny to T-case. Hope so.

 

Two adapters are available.
One long adapter and one short adapter. Both will work, but require the correct length in order to clear crossmembers and/or the transmission pan.
Longer is better, when installing a 205 behind an auto trans. This will barely clear the larger u-joint at the transmission pan, and the short adapter will not.
I always make new crossmembers anyway, so this is not much of an issue for me. I do not use stock x-members due to clearance limitations and front driveshafts with large joints. Pretty easy to make a x-member, but fiding the correct one is also a possibility.

There is some work involved with this swap, and using the incorrect adapter can limit driveline options.

I dont recall the C6 being available in anything other than a standard body / case with a standard length, I only recall the adpater that fits the rear being two different lengths.
I could be mistaken, but if a different length case were to be used,,,it would be safe to assume that internals would be a little bit different due to the lack of space?
Am I wrong here??????
Dave?????? Do I not have this correct? I may have to blow the dust off of the old books and see.

 

I think the tailshafts on the C6 are different between the 203/205. Maybe that was what he meant?

 

I would think so. Maybe I'm misunderstanding but wouldn't different length adapters necessitate different length output shafts in the trannys thereby making a simple adapter swap impossible?

 

Fordworth,
Good question!

 

Yes, there are 2 different ones and you also have 2 different length tail shafts for each one. The whole trans has to come apart to change one but internally there is nothing different in them other than the shaft.

 

I ran into the same problem of different output shaft lengths when I went to replace my dead NP203 ( '78 Bronco w/ a C6 ) with an NP 205. I got the t-case bolted up but it was then obvious that there was no way the front drive shaft would clear the crossmember. I had a T-18 4 speed laying around so I swapped that in. Much better now.