Thinking of swapping out my 69 transfer case Model 24 for a married NP205 and transmission. Any one tell me what I need to do this? Do I have to change front differential? Just had knee replaced so dang sure can"t crawl around anything but have a lot of time to think about things like this! Thanks for the help in advance!
Thanks for all Number Dummy does for this website!!

 

It's a swap I've considered for my 68 F-100 as well. I have the NP435 with Dana 21 single speed transfer case. Don't know why I need a low range with the granny gear, but I still want to do it. Not sure why you would want to go through the trouble of changing when you already have the Dana 24. It's a good transfer case and not really anything to be gained that I am aware of aside from being married to the transmission.

I can't tell you everything that will be required and someone will need more info about your truck to come close to that information. I can tell you that it will not be necessary to change the front differential to do this swap. The only reason that a front differential change would be necessary is of you changed the rear differential, need to keep the gear ratios matched.

In addition to the necessary parts for the engine and transmission, you would probably need to change driveshafts. I'm not even sure if the 24 and 205 have the same style of output flanges, but the ones in the truck now still wouldn't work because the transfer case has moved. Most likely a shorter front drive shaft and longer rear drive shaft would be required. Married NP205s were found with the NP435 in later model Ford trucks mid 70s+ IIRC, I'm assuming this is the trans and transfer case you intend to use. You might get lucky and be able to use driveshafts from a long bed (assuming this is going into a F-250) with the same engine/transmission/t-case combination, but by then wheel bases had changed so it might not work.

Folks are really going to need to know what you currently have for engine and transmission, as well as which transmission you plan to use with your 205. Even then there may be stuff you just have to measure and have made. IE: The driveshafts.

 

So you have a divorced t case highboy you want to swap to a married setup? What's the gain doing that? Its obviously doable with later 70's truck parts but why do it? If you want a NP205 just do a divorced unit.

 

Another problem with a married case is the driveline lengths will change if you use and older gear box, NV4500 not so much.

 

Sorry guys for omitting the truck info! Knee replacement meds messing me up.
The truck is a 1969 F250 4x4 Ranger with 4 speed and true 390 engine with 4 barrel. Tranny and transfer case rebuilt by old guy that has done these things forever. Worked for Ford in the 60's and 70's . All new bearing and gears that needed replaced were replaced. Thinking of married bcease less moving parts. Had a 71 F100 I put a 205 in and they are much quieter in the long run. That's my thoughts

 

If the trans and transfer case have been rebuilt already, they will probably last forever.

I understand the less moving parts thing, but how many moving parts are you really loosing. Sure you have a driveshaft between transmission and transfer case, but I wouldn't really call it a wear item and it's so short it's probably strong enough to pull a train.

Never compared a married to a divorced transfer case, so I can't comment on noise levels. I can't imagine a properly set-up divorced case being much worse in 2wd. Maybe in 4wd, but how much time do you spend there.

Not trying to discourage the swap, just want to understand the reason and gains.

 

Well one advantage you gain from the married swap is a better rear drive shaft operating angle if you ever lift that truck. You never said you were going to or have but that is a plus if you do. As you know the divorced case makes the rear shaft short and lifting it makes the operating angle absurd. I'm dealing with this now and I'm to the point where I want to rotate the rear pinion up and replace the single cardan with a double cardan at the case output. Since I just put a 10.25 in the rear and the spring perches are not welded I just may do this.

For your swap you will need to remove the current transmission mount and replace it with a later married style mount of sort. T-Case Shift Assembly for the married set up will be needed as well. Front and rear shafts will need to be changed for length as well. Maybe u joints depending on the case you get. Married case had a flange output in the front on some. One other thing to keep in mind the speedometer cable is not a direct fit from the 24 to 205 so you will need to get a 205 style gear and universal cable to your cluster. I bought a universal cable and Dakota Digital adapter for the gear with a threaded end for the drive and the cluster.

CStoyer

 

So I would not have tobreplace the front differential? That was my concern as I cannot remember how my 71 half ton was when I was 25! I realize that the drive shaft angle come into plays with a married case! I have never used a lift kit on anything in my life and at 66 with a new replaced knee, lift kits are Not a concern! I love the look of the 67-72 Ford and Chevy/GMC pickups and the ride height are already perfect in my opinion.
I thank you for the detail on parts needed for the swap. If you can think of any more let me know. As you know these trucks are tall even at factory height! Trying to figure out if I want to find another 67-72 F100 4x4 nd sell my F250 or what! It's a bear to get in and out of at 66! But damn I love it!

 

I understand there can be some potential movement of a divorced transfer case when under torque while towing. The solution is to put a brace in. I was considering converting to a married transfer case in a new 4X4 conversion that I'm doing just for that reason. Especially since I'm building the truck specifically for towing.

 

I did a brace on mine and there are lots of plate style mounts out there from fab places to do this. If you add this support you should not have any concerns of the case moving. Also, if you use a poly bushing for your support rod attachment points you can reduce the vibration, if any exists from the t-case being transmitted to the frame.

No, I do not believe you need to change the front differential. You are talking about the angle of the pinion vs the output of the case and not a gearing issue, right? I didn't check the output angle on my Spicer 24 case before I swapped the NP205 in but I believe they are the same angle. Someone may know for sure and answer it.

CStoyer

 

Thank you for that info.