I have a 71' F100 4x4 with an NP435 mated to a Dana 21.I want to put a NP205 behind it in place of the Dana 21. Can I just remove the Dana 21 and find a NP205 and bolt it up? What years did the NP205 come married to the NP435?

 

from about the mid 70s with the exception of the 3/4 tons , I believe all 1/2tons had the married units and it should be a bolt in although driveshafts may have to be altered.

 

Goodold71,I did that swap a few years ago ,here's what I had to do.First make sure the imput splines on the T-case match the output shaft on the NP435.Get the shifter and tranny to T-case tailpiecewith the T-case.The shifter hole for the T-case will need to be modifyed.I had to get a longer speedo cable ,I think it was from a 79 F-150 4x4.Either move the T-case crossmember back or do like I did and fab up a riser plate that bolts to the crossmember then remount the t-case swivel mount further back on the plate,I did this to give me an extra couple inches of ground clearance.The back driveline will need to be shortened .Make sure you get the side mount T-case rubber and steel mount that bolts to the frame,it's worth the time it takes to drill the holes in the driver side frame to mount it.Replace all the exterior seals after you have the case checked out. I rebuilt both drivelines as long as I had it apart,get the heavy duty u-joints with the flush zerks on the end of the caps,so much easier to find and grease.I left the front driveshaft alone as it was only about a half inch too short,if you have a lot of travel you might have to modify it. All said it was one of the best things I have done to My rig.Good Luck!
"bowties in the rearview mirror"

 

NOD, "remount the t-case swivel mount further back on the plate"
....what plate?? the tcase or crossmember? "Make sure you get the side mount T-case rubber and steel mount that bolts to the frame,it's worth the time it takes to drill the holes in the driver side frame to mount it." The np205 has the rubber mount that boilts to the side of it ,right? And then the rod that goes to the frame?What size ujoints? I am thinking of buying the ctm ujoints.Thanks for the help.It helped me make the decision to do it.

 

Goodold71,I used a length of 8' by 2' channel iron for a new tranny mount as the trans mount on the 205 is a couple of inches further back than the Dana 21.Mount the iron with the flanges up,bolt it in four places,2 front and 2 rear of the crossmember with about 3" hanging to the rear of the crossmember.I made a new tranny receiver out of smaller channel that replicated the stock receiver.Make sure it's centered where it needs to go and weld it in .The side mount on My 205 is made of two peices of angle iron,one will bolt to the frame and the other has mounting holes in the 205.There is no rod on mine,the angle on the 205 is above the angle on the frame with a rubber bushing in between the two angles and one under the bottom angle and these are bolted together using aircraft lock nuts or marceled nuts.I can't remember what brand u-joints i bought but they were the stock size and I got the heavy duty ones with the zerks on the end cap,I think all the heavy duty u-joints have the zerks on the end caps but don't quote me on that.I did use a 79 F-150 4x4 speedo cable,I had to regear the trans end as the gearing is different between the 205 and the Dana 21.The other end of the cable is a slip on instead of thread on so I cut the slip housing 4 times and hooked it on with a good strong hose clamp,it works great.
"bowties in the rearview mirror"

 

Nod, is it possible for you to send me pics ??Thanks.