I know these lock the shift rails toghether so you can't shift into 2 different gears but I'm just curious does any body have a picture or can explain how they work? I'm looking at this shift rail and theres a long groove on the front rail and 2 small ones on the rear. I just wondering what position the pills sit at diferent gears? It doesn't look like they would line up so thier in a groove on each rail at the same time. I'm going to grind the rails and leave the pills in so ican get front low only and i found out how to grind them but i want to see how it works before i do any grinding

I've never had a Dana t-case apart, so maybe its not the same, but if they work like a New Proccess, I can give you a discription of what they do and how they work. First off you have 3 detents in each rod that hold them in each position. A spring pressured steel ball is pushed into them at each spot. Do not confuse these with the interlock grooves. The interlock grooves on the rods are neccesary because there is only one common shift lever between the 2 rods. The interlocks hold one shaft in place while the other one moves, and once it has moved, it will open up a groove over the next rod so that it can now move. This forms a walking action of the 2 shift rods to get them both in the same direction one at a time. The motion of the second rod generally arrest the opposite movement of the first rod(primary or rear), so that when you go in the opposite direction, the last rod to move(front) is the first rod to move back so that rear wheel drive is always prevalent, and 4 wheel drive is secondary.

When moving to low, the front rod is freed up before the primary rod reaches detent so that it will shift and engage 4 wheel drive simotaneously so that the super high torque of the doubled down gear doesn't go to the rear axle alone. Since there is only one common shift lever, the case can only be put in the same gear on both shafts due to the walking motion just described, but if you had twin sticks, these rods would also prevent the case from becoming split, or one shaft high and one shaft low. A little extra grinding is required to defeat the both only feature of the low side and the rear first feature of the high side, so that either shaft can be put in high or low independantly, but the grooves will still prevent the 2 rods from becoming so far apart that one shaft could be ahead and the other be far enough behind to be in the opposite range.

Now that is on the NP-205. I would think that the Dana's would be similar as far as the interlocks are concerned, but I believe they shift differently. Never worked on a Dana 20, but I'm almost positive on the Dana 24 that the high and low is set up on the main shaft, and then the front output is then engaged or disengaged. Since there are still 2 shift rods, and those shift rods perform primarily the same function although they go about it by a different means, I would think the function of the interlocks would be largely identical to how I described it. On the Dana 20, I would think it would use either one or the other methods I described, so hopefully this is an accurate description of what you needed.

Grind the rails
http://www.wt4x4.net/tech/twinstick.htm