Here is a pic of the factory S-10 vacuum actuator:

Posi-Lok's previous kit simply replaces the vacuum lines & actuator, another cable & problematic pivoting mechanism. This old design connected to the factory diff cable. Here is a pic of how their old "2 piece" design connected to the factory diff cable, in place of where the factory vacuum actuator used to sit:

The problem with this kit is that it is difficult to install, and only addresses part of the S-10 front axle engagement problem. The problem most people are experiencing is that after the old Posi-Lok kit is installed, there is a tremendous bind when trying to engage the front axle, via pulling the Posi-Lok cable in the cab. Why? Doesn't really make sense, since the Posi-Lok cable itself moved in & out perfectly fine PRIOR to connecting it to the front diff cable! But.....the problem is actually still in 2 completely different places. The 1st is in the problematic pivoting mechanism pictured above, and the 2nd problem lies in the factory diff cable itself, that is still attached to the front diff. Why is the factory diff cable a problem? Because with non-use, or by living in a colder climate, these cables will simply rust or freeze up…..meaning that the cable won’t move! Here is a pic of the front diff cable that is often completely overlooked:

As stated before, with this cable frozen or rusted up, it does not matter what you connect to it.....it's simply not gonna work! That is where a liberal dose of your favorite lubricant comes into play.
Getting this cable to freely move can be a major challenge, depending on just how bad your specific cable is frozen up. If you cannot get the factory cable to move freely, you will need to disconnect it from the front diff, and try to get it to move freely. If the cable is still frozen up while unattached from the truck, you will need to replace it. If that does not work, then the problem would have to lie in what this factory diff cable attaches to.....but that's very rarely the problem. Here's how it's all connected. The diff side of the factory diff cable...

...is inserted into this factory plastic housing...

...like this....

...and attaches to the front diff right here:

When the front diff is not engaged, this mechanism on the diff looks like this:

When the front diff IS engaged, this mechanism looks like this:

See, the cable simply pulls this mechanism out to engage the front diff, and pushes it back in to disengage it. What does this “mechanism” actually do inside the diff? Well, it slides a collar over towards the passenger side, and simply locks the passenger side axle shaft to the diff itself.

The new posi-lok design:

It is a simple one-piece design that eliminates their previous problematic pivoting mechanism in their old kit, and replaces the factory diff cable with their new one piece cable. I will say that their new kit does function perfectly fine.....but, once again, the installation was IMO simply ridiculous.

What kinds of issues, you ask? Well, let's start with the very first step. First, their instructions tell you to drill an 11/16ths hole in a specific spot on the firewall (try not to cut any “under dash” wiring harnesses during this!), remove the mounting bracket washer & nut from their supplied cable, slide the mounting bracket onto the cable, and then re-install the big washer & nut back onto the Posi-lok cable, before siding the cable through your newly drilled firewall hole. This is where I question whether or not Posi-Lok ever even installed this newly re-designed S-10 cable…..onto an S-10!!! Why? The big nut on the cable cannot just slide right off of the new cable, because its’ inside diameter is smaller than the differential bolt head, that it has to slide OVER to be removed!!! I had to use my Dremel to shave down the corners of the brass bolt head, just to be able to remove the freakin nut. Unfortunately, you cannot install this mounting bracket, without first removing the nut….which REQUIRES you to shave down the corners of the bolt head! Here’s a pic:

Here’s a pic of the nut & washer finally removed after grinding down the corners of the head of the bolt:

And here’s a pic of the mounting bracket installed on the cable after putting it all back together:

Next problem. When I attempted to slide the cable through the 11/16ths hole they outlined for me to drill in my firewall, I quickly realized that the head of the diff bolt was STILL too big to fit through my perfectly round 11/16ths hole!!!! (It’s kinda hard to tell from the pic, but you get the idea.) Here’s a pic:

Sooooo, I got to dremel the brass head of the bolt down even more, so the diff bolt could slide through my hole in the firewall. Drilling out the firewall hole even larger was not an option, since it is obviously pretty important for the supplied cable grommet to fit very tightly in the hole. Here’s a pic of just how “round” I had to make the head of the diff bolt:

After routing the cable through the new hole in the firewall, I was next faced with the routing of the cable down to the front diff. The instructions are incredibly vague here, so you just have to have plenty of patience & common sense to route it correctly. There is a huge amount of excess cable left over…even while installing it on an S-10 with the 5” BDS suspension lift kit! In fact, I had soooo much excess cable, I had to route it inside the back of the front bumper for it to fit correctly, with no binding!!! Here’s a pic:

The last problem I encountered is the length of the actual cable itself. With the Posi-lok cable disengaged (meaning that the red button is completely pressed in), the amount of cable sticking out of the diff side of the sheath, was less than the factory amount of cable that extended past the end of its sheath. (Kinda hard to understand, but maybe this pic will help:

In this pic, the factory diff cable (the one on the bottom) is completely disengaged, meaning that the cable is depressed as far toward the diff as possible. The cable on the top is the Posi-lok cable, and it too is completely depressed. While this little issue does not really affect the installation, it is a MAJOR issue if you ever need to remove this cable from your front diff. In fact, because of their shorter cable, Posi-lok explains in their instructions, a special & complicated procedure for removal of their cable from the front diff!!! Now, I didn’t have to go through this “special procedure” when removing the factory cable from the front diff simply because it had adequate length! Apparently Posi-lok realized their mistake after designing it…and instead of just re-designing the cable to be the same length they just made the removal process a massive headache. They even included a “special tool” to aid in the cable removal. Because their cable is shorter, the engagement “stroke” (meaning the distance you pull out the cable from inside the cab) is pretty short. It’s actually a shorter stroke from their first design.

Here’s the finished product after installation:

Connected to the front diff:

Installed in the cab:

Now for the biggest question of all. How does it work??? It works perfectly fine! Very smooth engagement, with no binding whatsoever. My overall impressions? The instructions are still incredibly lacking, and their lack of R&D caused the install process to be a major pain , but it does work perfectly. It is a direct connection to the front diff. Pull the cable, and the front diff is engaged. Press it back in, and it is now disengaged.

I hope this write-up explains how your front diff operates, as well as the things you need to know about Posi-Lok’s cable.

Page submitted by : Jeremy aka Muslhed