My 1978 f-250 460 c-6 has a np 203 transfer case. I was wondering that if it is a full time transfer case, should i just keep the front hubs locked at all times or what? Does it make a difference? Also what kind of fluid does the np 203 take

 

The NP203 is a full time four wheel drive transfer case. It's chain driven instead of gears. It's also possible to convert it to part time with a kit.

 

Adam, Are you sure it is the NP-203 and not the NP-205. If your truck came with factory unlockable hubs then it shouldn't be a NP-203. they only came with plates to keep the front axle engaged all the time and the T-case had a Lo-Loc/Lo/Neutral/Hi/Hi-Loc . The Np-205 had 4-Lo/Neutral/2-Hi/4-Hi and had unlockable hubs. Running a NP-203 with unlocked hubs and it hasn't been converted to part-time usage will damage the T-case in the long run. It has a differential with a locking mechanism to allow for 50/50 power to both wheels. the locking mechanism isn't designed from the factory to have all the power going thru one drive shaft when the front hubs are unlocked for a long period of time. Hence the conversion kits to keep from destroying the Diff in the NP-203.Good luck.
Eric

Proud owner of a '73 F-250 4x4 High Boy, 460 V8, NP435, NP205
And a '68 Bronco 289 v8 , NP435 , Dana 20

 

so basicly if i dont lock my hubs the t case will mess up. if i lock the wheels wont it get worse??? i know its a 203 because i
looked at the tag on it.

 

The Np-203 was designed to be run with both driveshafts installed and the hubs locked ALL the time for it to run at all with the T-case in HI or LO (But not Hi-Loc or Lo-Loc). this was the early attempt at All-Wheel-Drive that you see now all over the place. The T-case had an internall differential to allow for the slight difference in wheel speeds between the front and rear axles while driving on pavement and turning. If the front drive is disconnected(unlocked hubs or drive shaft removed) then all the power will just spin the front output yoke just like an open rear end will spin one tire if traction is lost. Hi-Loc or Lo-Loc engages a locking mechanism in the T-case to allow for 50/50 power like the traditional Np-205. This is not very strong and will not hold up for too long if the front is dissengaged. It will still spin both front and rear drive-shafts. Get a Part time kit from MileMarker (I think), this will eliminate any problems with running in 2-wheel drive. then you can dissengage the front all the time.Sorry for the long winded reply. Good luck.
Eric

Proud owner of a '73 F-250 4x4 High Boy, 460 V8, NP435, NP205
And a '68 Bronco 289 v8 , NP435 , Dana 20

 

You got it alpo, not much to add.
If you can find a 205 swap it for your 203, its probably cheaper and definitely faster than a conversion kit.

If you didn't build it, its not really yours.

 

if i put a 205 in the truck will i need anything special to do it or will it just bolt into place???
also what kindof fluid do they take?

 

 

I need to know what has to be done to make the switch.

I have a 1978 bronco XLT with the NP205 as the donor.

The unit it would be going into is a 1979 Custom Bronco.

TIA.

Rick.

 

What is in the 79 bronco now?

 

I have had so many problems with my 203 case...

If you can, get the Mile Marker shaft kit. It is about $300. You can also convert it to part time with the Mile Marker 501 kit, but the shaft kit is a LOT better.

 

The NP203.

Rick.

 

Apparently you have to put your transfer case into 4 wheel high every 200miles or so for 10 miles or some of the components in the NP203 transfer case don't get lubricated.

For that reason I think it would be better just to change up to the NP205 part time transfer case.

What I'm looking for is someone who has done this switch who can give me some kinda idea of what's involved with such a task.

TIA, Rick.

 

I hit you back in your other thread regarding this topic.
As far as locking the front hubs, or engaging 4x4, yes it should be done occassionaly for the 203 with a part time conversion.
Should also be done periodically for any combination of part time 4wd. You need to keep seals conditioned, bearings lubed, u-joints excersized, lockouts rotated, linkages operated, etc. etc. etc.
Seen many 4x4's simply not operate due to a lack of use.

 

If you have the means of doing it, definately swap in the 205. I have all of the parts needed to do the swap, just don't have the tools,etc. to do it. Now that my case is converted, I love it.