Divorcing a Dana 18 or Dana 20

[1979C20]

Okay, just a few minutes ago someone recommended a divorced transfer case in order to avoid the issue of a 2wd transmission conversion. My dad has a D18 and a D20 on the side of the house. Novak and Advanced Adapters make an input shaft yolk adapter to divorce them, but I dont have 500 bucks! So, what would it take to do it on my own? and I have a family friend with a machine shop, I could go to hime and get part CNC'ed fairly cheap if needed.

[VileZambonie]

What are you trying to do? I wouldn't run a dana 20 in anything other than a strictly offroad pile of poop.

[1979C20]

Well, I have a 79 2wd with posi in the rear end. It has a 4spd manual with granny low (6.55:1) and 4:11 gears and going up or down hills during light offroading, its still geared too high. So, I'm looking to add one of those two t-cases that are on the side of my house to my truck via divorced, just to lower my over all gearing. And, hopefully, in the near future I am going to do a 4wd conversion by swapping the front drive train with solid axle and suspension. So, I figured I would start off my 4wd conversion by adding a transfer case, since I want lower gearing already. And, I'm on a budget for this truck. So, I'm trying to make do with what I have already.

[Blazin]

Don't waste your time or money with either of those cases. They are fine in CJ 5 / 7 etc. but not heavy enough for a full size truck.

[4x4orbust]

yup, what blazin said...   keep an eye open for a np205 or 208, they can be had fairly cheap.   if you look around enough, you may find a manual tranny with a t-case together that you can swap right in place of yours.  you are going to need a new rear driveshaft (or one from the junkyard that fits your application)

[NevadaNeal]

Aww you guys hurt my feelings  . I have a Dana 20 in my 75 F100 and it has held up just fine behind the 390. it was a bolt in swap in place of the single speed Dana 21 that was in there.I added a Teraflex 3.45.1 set and Novak twin-stick setup and i love it.
The only Dana 20 that i  know of ever being in a gm was the early blazers. If the transfer cases you have are divorced then my best guess is they came from an International or Jeep truck.

[1979C20]

These are not divorced, and they came off of a CJ and an IH Scout. I was wondering what it took TO divorce them.

[NevadaNeal]

It would probably easier to find a tranny that you can adapt them to. You can find parts pretty easy to mount just about any tranny behind a small block. You would be money ahead that way.The sm465 you have in your truck was also used in Jeep trucks. Or find yourself a married unit at a wrecking yard some where.
The Dana 20 is a great case.Strong,light,and a good aftermarket support. I do agree with the guys on this board though. Sometimes just because you already have it does not justify the headache.
Keep your eyes peeled and stay on the hunt..you may find a bolt in swap.

You said you want lower gears. Low is all a matter of opinion...how low do you want to go?  The dana 20 has a low range of 2.46:1 while the np205 has a low of 1.96:1  and the np203 has 2.00:1. Both the np205 and the 203 came factory in 70's GM trucks.

[1979C20]

Well, The sm465 I have is the 2wd one. You cant marry anything to it unless you swap the output shaft and buy an adapter plate. And I really love the transmission. Its got great gearing and its in great condition. When I resealed it, there were no metal shavings or anything in the bottom. And all of the gears and synchros look great. The truck is a 79 and it sat fro ten years. So not much wear on the whole truck. 60k original miles. so, I was thinking, either divorce one of the tcases i have, or find a divorced one.