Long story short, I'm frustrated with my electronic transfer case. It has numerous issues and it is finally stuck in 4lo and will not disengage. When I bought the truck, the previous owner included a np231 tcase from an S-truck. So, since I needed to pull the 233 to change the input seal, I have decided to swap to a more reliable mechanical setup. I plan on going with a cable to lock the front axle as well. I have a few questions though.

If anybody has done this swap, is there any problems with using the stock mechanical linkages from the junkyard? I just want everything to work smoothly, and if it would be better to go aftermarket for a shifter then I would go that route.

Also, my truck is a 1994, and therefore uses an electonic Vehicle Speed Sensor. The T-case I have has an outlet to be cable driven. Haven't tried sticking these together, but will it all work together? Or will I have to swap some internals to the np231?

 

Why not just remove the encoder motor and weld up a linkage to the shift sector shaft in the NP233?

 

Well, I don't really have access to a welder right now. Also, I was going to take the case down to change the input seal since its annoying to be draining the excess ATF in my t-case and worry about checking the ATF all the time.

I already have this np231 case sitting in my basement which I got for free with my truck so It seemed like a better idea to go that route and use a stock-appearing shifter setup.

I did see this setup: http://www.zr2usa.com/mboard/index.php?showtopic=11695

but welding a wrench to my existing t-case didn't seem like something I wanted to do

 

On a side note, would anybody be interested in a formal writeup of the swap?

 

Write-ups are always welcome!

 

In 1994 models either transfer case was available so whatever you need is probably going to be possible to get. The indicator system is different as well as if you have an earlier model 231 you have the cable drive. But you know this. I'm looking at the factory Service Manual and Unit Repair Manual they both just show a t-case with a speed sensor so I guess it shouldn't be a big problem to replace the cable drive with a tone wheel and VSS. Fortuneatly you're going this way and your Blazer is already wired for the VSS. Pulling the rear case off one of these is pretty simple. I resealed the case halves and pump and extension housings on mine. Simple job. Just make sure the oil pump pickup tube is in place. It fits in a little niche in the bottom. Recommend you put it together with Locktite sealer instead of just silicone. Someone did a silicone job on mine and that's why I had it out. Good luck on the swap. Keep us posted. If you need some book advice post again.
By the way you can buy whole 231 t-cases on e-bay for like $150.00 sometimes. Good choice.