What all is invloved in swapping from a Dana21 (yuk!) to a NP205? I have a 72 F100 w/ a NP435 tranny and a Dana21 T-case and was really wanting a low range. I know of several 205 T-cases I can get so I wanted to know how difficult it would be to swap them. If this is going to be a royal pain then does anyone know of an easier swap? I'm not running 44's or nothing so absolute strength is nice but not nescisarily needed. I would like something that will hold up to a big block and probably 38's someday.Thanks.


"Like a Rock"; on the sides of roads everywhere.

 

I don't have all the details, but the NP205 came stock on the F250 and was a divorced type. the 73~79 F250 uses three drive shafts and the 205 mounts to the frame. Get the thick cover and brace if you can. The easiest way is to get a complete setup with mounts and drive lines. If your NP435 has married TC, then you'll probably need to get the back part of the tranny too. Don't forget the shifters as well.
The NP205 is considered king of the hill, it's VERY strong and would be an excellent upgrade.

4Wheel & off-road says: the bolt pattern on the 435's case for the Dana 21 if different from the 205 and are not interchangeable.
So I guess it depends on you're setup, If you have a driveline between the tranny and the TC, I think it would be a straight forward swap, otherwise you'd have to get the back part of the 435 or swap the 435 too.

 

Starting in '78 all Np-435/Np-205 were of the 'married' style like your Dana 21. you probably can just use any set up out of every thing from the fullsize bronco thru F-350. Grab the Tranny and the T-case plus the crossmember and go at it. You will probably have to modify the cross member and deal with midifing the driveshaft(u-joint size and or lenght). 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

 

I installed a 79 np205 into my 71 F-100 4x4. I got the married tranny,tailshaft,shift linkage,tranny floor pan that is for a np205,tranny mount and the rear frame mount for the trans case.Driveshaft will also need to be shortened in the rear, my front shaft was ok.I had to fabricate the trans case mount to the crossmsmber, it's a simple swivel connection but make it as strong as you can, I used thick wall channell iron and flatstock hard plastic on mine.Make sure you get the back of the transcase as high as possible but leave enough room for flexing.The rear transcase mount was a snap as long as you got the whole thing including the frame mount.After you locate the case on the main crossmember and make sure all the shifter positions are ok and the drivelines work,make sure the floorpan fits with no rubbing, bolt the frame bracket to the frame, make sure you leave the rubber doughnut in when you locate the bracket.The old backup light wiring went right on.Make sure you replace all the clips ,cotterpins and misc hardware with the best stuff you can find, you will be glad you did.I had to buy a longer speedo cable from a 79 4x4 I think , I had to modify the speedo end at the speedometer and use a hose clamp to keep it on and it worked quite well. Good Luck,it is worth the time .I had the trans case checked at a local 4x4 shop before I installed it.
"bowties in the rearview mirror"