I have a 78 F-250 with a married 203 that died. For sale locally is an np 205 (married also to a c-6). What will it take to put the np 205 in my truck? Will it even bolt to my c-6? Are the np 203 in my truck and np 205 in the other truck different lengths? If so, does this just mean lengthening the rear shaft? Lenthening or shortening of the front shaft? Are my yokes the same as the np 205? How about the t-case mounts? What about a shifter? I know, lot of questions.

Any help is appreciated Thanks

Tim

 

Everything except the input splines and adapter bolt pattern are different. Shifter is different since the 205 just uses a single shift linkage and the 203 has two.
The 203 is a very large case compared to the 205, and this will have an effect on both driveshafts. Yokes might have the same size u-joints, but the yokes do not interchange, so since you are modifying the shafts, you can just have the correct end put on the shaft so the thing will match the yoke.
Double cardan yokes are different than single joint yokes, so you will have to obtain the correct ones. Not all that difficult really.
As far as the mounts and such, you will need the brackets for the 205, as the 203 also uses different ones.
There are several holes that will line up with the new brackets, but I do remember drilling a couple for the correct fit.
Pretty straight foward swap, but can be a little time consuming, considering all of the work required.
The 205 is a much better case than the 203, and this is well worth the effort.

 

Not sure if you F250 will be the same as my F100, but I just did the same swap. Like 75F350 said the drive shafts are different, the bracket on the frame is different, and don't forget the cross member is different. Also, on my F100 the 203 had a single drive shaft to the rear. The 205 had a 2 piece drive shaft. So you will need the stuff for the carrier bearing. My parts truck had a steel plate and steel shims to help the angle of the drive shaft, that went between the carrier bearing and the cross member.

I had a complete parts truck when I did mine, so I just robbed parts as needed. One thing that I thought that would be different that wasn't is the cover on the floor over the shifter. Mine was the same for both t-cases.

All in all it wasn't that big of a challenge to swap the t-cases. The biggest chore was actually removing the cross member for the 203 t-case. The 205 cross member fell right in.

Good luck!!!

 

Well guys, thanks for the info. I am jumping in now that I see there is at least some water in the pool..... Since my 203 front driveshaft already has a double cardan joint, I can use that shaft right (with some mods).

 

The transmissions are DIFFERENT!!!! Been there done that!!! I own 4 1/2 78/79 Bronco's (One Doesn't have a body!!!) My 79 Free Wheeling Package Bronco had the C6/203 Combo...Chain Broke...I had another 79 sitting out back with C6/205...So I pulled the Transfer case off of it..went to bolt it onto the C6 of the Free Wheeler and it hit the cross member...I started looking..checked the other one...and sure enough there is a difference in length...so I pulled the C6 from the other and swapped both of them into it.

Also watch out...Some or possibly all 78's use smaller u-joints than 79's unless this has just been with the ones I own.

 

I had an issue swapping mine. went to bolt the 205 to my 203 flange no problem except that the nottch for the shifter linkages is in a different place. instead of grinding it out larger, I must have got lucky and taken the 205 from the same type c6. 77-79 mine was an f150 and the 205 came from a bronco.
I just scored a 460 bell, clutch, rebuilt np435 mated to a np205 with all the pedals driveshafts, brackets, and linkages for $100

will probably end up with an extra C6 4x4 tranny.
goodf2@yahoo.com in Omaha ne
It was working fine. had it rebuilt by a shop that 1:resurfaces the steels (wrongwrong wrong)
2:installed an imported valve body instead of cleaning and rebuilding the original ford unit.
problems with erratic shifting turnd out to be a warped valve body. they fixed it under warranty but it upshifts too fast when in drive and hangs in 2nd AND 3rd when shifting into 3rd when in drive. if you shift it manually the shift point doesn't match the detents. good tranny to rebuild right and put a stock valvebody back in. It still works but is annoying. I love 4 speeds