Got this 69 F100 with a blown engine, got a good used engine to go in it. Now I realize, it's only got a single speed transfer case. I'm pretty sure when it's back on the road, and trails, it's going to need a two speed transfer case.
Do you have any advice on what to start thinking about, and what to start looking for, in order to make this swap?
69 F100, 360 4 speed, with a married Dana 21.

 

VictorL,I bought a 71 F-100 4x4 with an NP 435 gearbox and a single speed trans case in it and decided to swap in a 79 NP205 married trans case.I got the transfer case with the NP435 and tail shaft it was married to so there was no other issue with spline count or length of shaft,I also got the shifter with it.Do not forget to get the NP205 to frame mounting brackets and rubber insulators that go with it.I had a hump cover out of a parts truck that had an NP 205 married to go in too.I had the tranny and transfer cases inspected and resealed before installing,paint also.I needed a speedo cable for a 79 bronco as the old one was too short,had to modify the end that goes onto the speedometer as the newer cable has no threads.I had to modify the transmission mount to the cross members the new setup sat about two inches or so further back.I took apart the stock tranny mount and used the part that bolts up to the tranny tailshaft. I took about a three inch length of C channel that the upper portion of the mount would fit down over,think it was one and a half or two inch channel,and with the flat side up I set the mount down over the channel and about centered the mark for the hole in the side flange of the channel.Make sure you leave enough room for full movement of the tranny mount,use a grade 8 or the stock mount bolt if you have it.If there is any space left between the channel and the inside width of the mount use some hard phenolic plastic to make a spacer or washers if you cant get phenolic.Now after the tranny and trans case are installed the tranny mount can be finished. I jacked up the tranny so it was up out of the way,the new tranny mount needs to be bolted to the tailshaft adapter now.I took an 8"X8" square of 1/2" plate steel and set it up on top of the crossmember where the old mount bolted on,make sure there is enough plate sticking back to weld the C-channnel to then center the hole layout for the crossmember bolts and drill the holes.I used the original bolts and bolted the plate down to the crossmember.Now I lowered the tranny down to the steel plate,make sure you center the tranny mount to the same center as the old tranny,then I tacked the C-channel to the steel plate then removed the mount and rubber parts and welded the C-channel to the 1/2" plate then reinstalled.I had to drill 3 holes in the frame on the driver side for the 205 to frame mount to work.Had to shorten the rear driveline about 6" but mine is a shortbed so yours might be different.Hope this helps.

"bowties in the rearview mirror"

 

Wow, thanks for your detailed breakdown on the NP205 swap. You tell it like you just did it yesterday.
It's good to know that you made the 205 swap from a later model truck.
Thanks again, there will be more questions still to come.

 

My 70 f100 has a 360, np435 with a dana 21 and I get around on the road and trails just fine. Sounds like alot of trouble and expense to go through.

 

Yeah, after researching the NP435, the 668 to 1 first gear sounds like it should be plenty. Cant wait to get er going.

 

it all depends what you're going to be doing, and how any other trucks in your group are equipped.

if you hang out with other people that have an NP435 and an NP205, you'll find your Dana 21 inadequate.

I did the same swap in my 69 F100. I originally had built my own crossmember because there was not enough room between the stock mount and the floor and also as was already stated it sits much further back than the original. I recently went back to a stock crossmember to make the D.O.T. less trigger happy, I cut up a piece of box tubing to mate the transmission mount to the crossmember using just the rear two bolts.

I've yet to figure out why its different, I haven't had a 73-79 F150 to figure out where the difference is, I suspect the motor mounts and clutch pivot ball are mounted a bit forward of the 67-72 position because the crossmembers are the same and are in exactly the same position in relation to the front axle dictated by the same radius arm length.

 

That's the thing, once you get out on the old logging roads around here, you need as much gear as you can get.
Is your NP435/205 a married unit? If so, is the 435 the original to the truck? I here the tail housing bolt pattern is different on the transmission depending on if the transfer case is a single speed or a two speed. I know where there is a 70 F250 4 speed with a divorced transfer case. It hangs down about a foot below the frame, but the transmission tail housing bolts should be the same, that is if it's true, that a 2wd truck, a 4wd truck with a divorced transfer case, and a 4wd truck with a single speed transfer case all share the same transmission tail bolt pattern, but the NP435 is going to have a different bolt pattern, when its married to a two speed transfer case.

 

Im tryin to do this same swap in my 68 f-100 wheelin rig, i had been told that the dana 21 was a good all around unit by some so i didnt get in a hurry to find a 435 with a attached 205, then this happened.




Interested to hear more about these swaps, and hope i can find a good deal on a tranny and t-case around soon.

 

What did you do, bounce yer truck off of it? A dana 21 is sufficient for a stock truck, If you are building an off road rig that's modified then I could see making the swap.

 

The case didnt make any contact with anything. My truck is lifted 6 inches and has 36s, i was going at a slow speed and there was just some binding issues due to some large rocks, and bam all at once jut cracked like a pumpkin an put a good sized dent in the bottom of my floor as it rotated up when it broke.

 

Man that thing sure did crack open like a pumpkin.
Do you know what approach you are going to take to get her going? Probably depends on what parts you find.