D-20 linkage problems Twin Stick solution?

[OLD 9]

My 79 CJ is stuck in 4 high. The Transfer Case linkage on the Dana 20 has a broken bolt. It's one of the square headed bolts connecting the linkage to the shift rods on the Transfer Case . The regular bolt I used to replace it promptly failed. I've searched locally and on the internet, even the Dodge store and can't find anyone that sells this bolt. I'm happy with my single stick but may have to upgrade to the twin stick unless someone knows where I can get a couple of these bolts or even a complete replacement linkage. The Jeep is my daily driver and I've been using it with the hubs in free.
In researching the twin sticks I've got even more questions. Seems there are a number of choices, long sticks, short sticks, different tranny applications, etc. The CJ has a T-18 and 360 from a 76 J-10 so what do I buy? The Transfer Case is original to the CJ. Is there an interlock to prevent someone from running low to one axle and high to the other? Do I need to pull the Transfer Case ? Please help and give me your opinions. This isn't a hard core 4X4, just a driver and weekend toy and I'm just a guy with a driveway. Wish I could find a replacement stock linkage.

 

[BusaDave9]

I'm confused what square head bolt you are talking about. The only square head bolt I know of on the Dana 20 are these 2 bolts that hold on the tubular bar that extends out the front of the TCase.

In the red oval in both of these pictures.
These bolts are sill needed when converting to the twin shift levers.

These square head bolts are somewhat pointed. You can grind the tips of 2 ordinary bolts to do the same job. These points go into recesses in the tube.
To answer your 2nd question; yes you can install twin shift levers without removeing the TCase. It's a little awkward but it helps to remove the Transmission access panel on the floor of the cab.

 

[OLD 9]

Thanks, Dave. It's been below freezing here in SL,UT for a while now so with my driveway covered in snow and ice, I took it in to 4 Wheel Parts. Their tec said the bolts were square headed and tapered and one had broken off. They said that they were unavalible but they made something that should work ($AMC 150 ). The fix lasted a week. Called them back and was told it was the bolts connecting the linkage to the shift rods (probably not the right answer) Guess I'll have to buck-up and go look myself, the Transmission access panel only has one screw in it right now. If the weather dosen't break soon I may take it down to Quadratec and see what they can do. Thanks again, probably are the square bolts on the tube but I think there may be more to it than that.