Transfer Case Swap

[Belvedeer]

Well I recently bought a 68 F100 and if course I love it. But the one thing I dont love is the transfer case only has high range.

So what I am lokoing for is what transfer case might I be able to swap in that has low range.

I currently have a 4-speed manual and the transfer case is married. The truck has a 390ci and I'm looking to with that motor.

I just need the easiest and most affordable way to get a transfer case with low range in the truck.

Any advice is welcome!

[xxxtina63]

Ahh, the old single speed. The easiest swap would be to locate a NP205. They came behind manuals and autos, although manuals seem to be more plentiful with 4x4's. Not sure if there would be many differences, but I'd say try to find a complete assembly from an F100/F150 up to 1976. Be sure to get the trans adapter, t-case, crossmember, shifter linkage, and driveshafts if you can. This will save you money and headache later on should you find some parts are not interchangable. Also, around 76-77 Ford had the NP435 trans, probably not the one you have, although some parts may be interchangable.

[hutch1973]

I'm going to do this swap within the next month or so. I have a complete 70s F150 with the hi/lo loc transfer case I'm using as a donor. The single speed works fine, but the noise from the gear on gear is annoying. I'll post when I do it.

[averagef250]

The gear-gear cases don't make any noise if they're in good shape. A 203 with a sloppy chain is pretty annoying too. Always thought the only reason to run a 203 was if you're truck came with it and you didn't have the time or money to get rid of it. The single speed Dana 21 case is a real pile though. I've heard you can take a bone stock F100 4x4 with a 360, 4 speed and the single speed case, put it in reverse, dump the clutch and not go anywhere because your dana 21 just blew into six pieces and both drivelines are laying on the ground. I'm working with a friend putting a 700 horse 460 in a 73 F-100 that has the single speed case. We're not even gonna try to move the truck with that case. It'll get replaced with a 205 as soon as we find one.

[hutch1973]

I've had 3 different 21's and they were all loud (to my ear, anyway) compared to the chain driven. I've also heard the opposite about the durability, that the gear on gear was bulletproof because there was so little to go wrong?? I've never had any issues with any transfer case performance wise, but I'm also not an avid off roader and don't care about ultra heavy duty performance. As long as it gets from point a to point b, makes enough noise to piss off the neighbors, I'm content.

[4x4_Welder]

Does anything else actually bolt up where the D21 came out of?

[averagef250]

I'll ask my gear man today if the 205 is a bolt in or not. I'd almost guess it would be. You can bolt a 73 NP205 to a 2007 ZF 6 speed behind a powerstroke. The Divorced NP205 is a direct bolt in for a D24. Ford liked to keep transmissions simple. Why they couldn't do the same for bellhousings gets me though.

I've never actually owned an F-100 4x4, I have just heard over and over how much of a pile the D21 case is. I've owned more D24 and D23 cases than I can count and they're pretty quiet, not real tough though. The ford 32 spline NP205 is pretty hard to break.

Hey Jared, What are you going to use for intake and controller for FE port injection?

[Sharps-Nut]

What about a t case from a early bronco. They are high low case, i am sure they are gear drive just as the np205 are. I had a 74 bronco with a 302 and the case was very quiet, easy to use and neer had to do a thing to it from 1991 when I bought it till 11-15-05 when I sold it. Just a thought.

[4x4_Welder]

I just picked up a D24 case for less than the cost of the gas to get it. It almost looks like it's machined for a mounting pad on the input side, I have to clean it to be sure, but it might be possible to attatch it directly to the transmission. I don't care if I have to drill the case, that doesn't freak me out in any way, but I have to wonder if I'm barking up the wrong tree here. Did anybody (Dodge, Jeep, GM) use the D24 mated to the tranny?

[averagef250]

Think D18 and D20 were the only mated dana cases, but could be wrong. Chevy and ford used the D23 in thier pre-59 Napco conversion 4x4's, but it was also divorced. I have rebuilt many 23 and 24 cases and I could definately say that a 24 shares nothing in common with a 205(except the mounting studs). The shaft splines are all very coarse on the dana cases. If you need any more dana 24's and want to drive to Portland, I can fill the back of your truck.

[Rockcrusher]

Does anything else actually bolt up where the D21 came out of?

Nothing stock will bolt up. Your transmission is the 2WD flavor which means the output side has a rectangular bolt pattern. AA and maybe Novak sells adapters for various transfercases.

I wouldn't hang a Dana 18 or 20 behind an FE motor . . . You might wind up with a weapon of mass destruction.

[Belvedeer]

Really alot of great info here. Gives me some things I can look up... and once I get time to actually work on the 68 and do the swap I'll be happy. Thanks again for the info!

[pat67shorty]

Go find a late NP435 from a 70's truck. It has a lower first gear than the T-18 anyways. Then any 6 bolt ford t-case will bolt to it. NP205, NP208, BW1345, BW1356, ect.