most of these were sold in cities. Where low range is like "whats low range for daddy?" "your grandma" See, they dont even know what i does.

 

My 74 had a single speed it was a F-100 SB. It also had a four speed with first gear being grany low so it wasent too bad. Why would you want to use a 203? If you are going to change do it right and put a 205 in their. The 203s are junk the use a chain that unlike the newer chain drives will streach and they are a full time case which means if you want to run it as a part time case you will have to buy a conversion kit also they are very heavy. The 205 is gear to gear no chain and are a part time case to start out with also they are alot lighter and and easy to find. As far as adapters go I dont know what bolt pattern the 21 t-cases use but if its the standard round pattern that Ford used for years and the 203 and 205 use it should bolt up.
Leadmic

 

My 1975 Ford F100 4x4 4 speed had this transfer case. It would shift from 2H to 4 hi. It was very good and durable tranfer case (Dana 21). https://www.ford-trucks.com/user_gal...=95833&width=0.

baily034, What size of motor was mounted to this C6 Automatic Transmission?

 

Thanks for all the comments. I got a 205 transfer case and a matching 4 speed transmission. Installing it this weekend.

There was a 400m with the C6 auto and 203 tc. Parts truck.

The truck we are working on has a 300 6 and 3.50 gears.

 

It is a penny pinching move I am sure, but think about it. If my granny low is 6.2 or whatever it is I dont need much reduction. Hell put a c6 with a 2 speed t-case in and in 4-low I will still have a lower gear. Still in search of two speed swap though. How do you like 12 to 1 hahaha.

 

The NP203 transfer cases are not junk. They are not as strong as the gear to gear NP205's but are very strong none the less. I owned a 1975 F250 for 20 years. It had a 390, C6 and NP203. It was my daily driver and used for many weekend off-roading adventures. The truck also went through many harsh winters. The Full-time NP203 was changed to part time for better mpg. I never had problems with the chain breaking or even stretching. I will agree that the NP 205 is stronger but don't sell the NP203 short as they are very strong.

 

tomcasino, could you tell me what oil goes in the 203 and how much?
Is it 30W and 7 quarts, I can't remember, thanks.

 

Hello MBBFord, I just changed the fluid in all of my gear boxes about 6 weeks ago. I used 80w90 Valvoline in the diffs and 10w40 Valvoline in the NP203. The Haynes manuel says 140w but that's too thick. I've heard to use from 30w all the way up to 140w. Someone had a very good link on the NP203 but I just can't find it. It's very cold in Saint Paul right now so the lighter weight works best for me. By the way the manuel says 9.0 pints for the NP203. Mine didn't seem to take that much. It might not have been completely drained. Hope this helps.

 

Had to go pull "1975 The Ford Shop Truck Manual" recommendations
For the NP 203 Transfer Case.

It does make sense in using the lighter weight oil on the NP203, due to the chain drive in the NP 203 transfer case. This chain will require a lighter oil.

as per manual, SAE 50W engine oil if the temperature is above 10 degrees F.
SAE 30W engine oil if the temperature is below 10 degrees F. This was based on a 1975 FORD truck shop manual.

I conclude oil currently processed exceed any oil made in the 1970's. It will mostly like be safe to use SAE 50w oil in the winter and summer.
__________________________________________________ ___________________
To check if your transfer case has gear oil. The Gear oil will have a characteristic aroma, due to the addition of molybdenum disulfide compounds, to lubricate the many parts of sliding friction seen by the teeth due to their helical cut, which in turn is done to eliminate the characteristic whine of straight cut gears.

I have personally used 80w90 gear oil on my NP205, due to the lack of my Shop Manual for reference. The characteristics of this 80W90 gear oil looks very good as per oil spec sheet. And have had no problems with my Transfer Case NP205.

Question, How much transmission noise or transfer case noise is directly associated with the use SAE 30w or SAE 50w.

 

1975 The Ford Shop Truck Manual" recommendations
For the NP 205 Transfer Case is SAE 50W engine oil.

 

MBBFord, here is that web address for the 203. It says Chevy but it's still a good article. Just paste this in your browser. http://www.off-road.com/chevy/mm-np203/

 

thanks for the help guys, and tomcasino, I've read that site before, and I'm pretty sure I have the cheap crown gear conversion kit in my bronco, and it has some good info in there too.
I have a chiltons manuel that says the use 90W in the 203 but no amount.
I know 90W is way too thick for me, and I think I'll use 30W.

 

The legendary Dana 21. I never thought I'd hear about those again. It might be worth something; there isn't many of them around anymore. But then again, probably for good reason: lol!

 

LeadMike,

An NP 203 junk? Hardly, they are heavy and way overbuilt. You will blow more Dana 60s in the rear than you will blow NP 203s. I have over 325,000 miles of hard towing, wheeling, and a lot of four wheel drive use here in Alaska. There are a lot of the 203s up here in the wrecking yard. If you need me to make the connection for you it is because nobody needs one because they almost never fail. To be fair, there a lot of 205s also. I agree the np 205 could be a better engineered transfer case on paper. However, in practice, they are both nearly equal for the average user.

 

They are too heavy almost 300lbs., the chains streach and jump I have seen this happen twice, you can buy an aircraft quality chain aftermarket for it or at least you used to be able to and then your good to go. To convert one to part time it costs 200.00 dollars just for the kit and then you have to install it , then you have to put in 4X4 every 200 mles or you will burn up the rear bearing. You can get a good used 205 all day long for 200.00 dollars that weighs a little over 150lbs and has no chain to go bad or kit to buy and is truly bullet proof. The 203 is good for one thing though you can take the plantary part off and buy a adapter kit to bolt it to a 205 and make a doubbler out of it.
Now honestly if you were looking for a transfercase to put in to somthing that had eather a broken or missing one would you even consider putting a 203 in it? If so why?
Leadmic