How to Put an Atlas (or Dana 300) Transfer Case on a TH350 ... The CHEAP Way!

 

Since I got rid of the doubler that used to be in Patooyee, I found it necessary to adapt my Atlas II transfer case to my Chevy Turbo 350 transmission while building Patooyee II.  There are a few companies out there who make custom adaptors that cost a lot.  I am forever a penny pincher though so I was bound and determined to do it some other way.  I had heard before that it is possible to use a stock TH350 - NP208 adapter to mate a Dana 300 t-case to a TH350 by simply bolting up the adaptor and buying the spud shaft that would be required from one of the companies who make the adapters.  And since my Atlas II replaced a D300 exactly, I figured it would also work for me.  Some people said it would not though and this article is to show otherwise. 

 

This is a pic of the NP208 side of the stock Chevy TH350 - NP208 adapter.  A slight modification of one of the holes is necessary to use all the bolt holes in the t-case.  You can see it at the 10:00 position here.
Here is the front of the Atlas II.  To be honest, I'm not really sure which set of holes in it is the stock D300 position, so I don't know how a D300 would end up being clocked using this setup.  But with the studs where they are in this pic my Atlas II is a little above flat.  (About 2*.)
Here is the back of a TH350, just for those who have never seen one before.  The stock adapter fits this perfectly.
Here it is ... living PROOF that this adapter works.  With the small hole modification I was able to use all of the bolt holes on the Atlas II. 
There IS a slight problem however ...
... the front driveshaft comes awfully close to the tranny pan.  The yoke you see on here now is a 1410 yoke, so if you're using a 1350, 1330, or a 1310 joint with a smaller driveshaft you may clear it.  Or if you're mounting your own drive train you could mount it at a slight angle so that the driveshaft travels away from the tranny pan.  Patooyee II is designed such that I don't think it will be a problem.  Only time will tell for certain though.
 

********* UPDATE *********

I now have the spud shaft sold by Novak Adapters installed in my home-brewed adapter.  It fits flawlessly.  I have been told that there are 3 different 350 - 208 adapters though and that it may not work in all adapters.  I have not found this to be the case but have little experience with any others than my own.  I can say that in my adapter it works great.  Click here for a link to the Novak kit that contains the spud shaft.  They do sell the shaft separately.

Some company's aftermarket adapters have a special bearing that the spud shaft rides in that requires additional machining, thus making the adapter more expensive than the second type, which has no bearing for the spud shaft to ride in.  The companies that use the bearing claim that the bearings on the tranny and t-case will have a longer life than if the bearing was not present.  The company's that do not use the bearing normally claim that they use involute splines to ensure that the coupler rides perfectly centered on the two shafts.  Real-world experience of people I have asked is that, after thousands of miles of use, NEITHER of these designs have had any problems.  The cheap way that I have used in this article uses no bearing.  I don't anticipate having problems, especially since my vehicle will never see the 1000 mile mark.  (Or even have an odometer for that matter.)