There have been posts regarding this brake conversion, and the weak emergency brake.
This is what I did...
On the extended cab trucks on the driver's side where the cab meets the bed, there is a 15" cable with 1" by . 5" ends on it that connects the e-brake cable from cab, to the e-brakes on the rear axle.
I looked at that and rather than cutting the ends off the cable at the calipers, I decided to shorten this cable.
I went to the dealer thinking I could look through the parts catalog and get one from a different cab config... so I ordered one, and got the exact same one I had on my truck...
Ok, so I thought maybe someone could build me this shorter cable... after some internet searching I found
Madison Power Systems. I told them what I wanted, and they said it would be easier to figure out if I sent them my cable. So I sent them the one I bought... $12 later I had a 9" cable.
After I hooked it up and pressed the pedal, it took up all the slack, and I still had too much play to make the caliper ebrake work right.
I sent them the one off my truck and asked them to make an 8" and 7" one. $25 later and I have two cables to try. The 8" one attached fairly easily, and did engage the caliper ebrake, but only moved the arms about 1/4"... not near enough to hold anything.
So I tried the 7" one... It was too short... I couldn't get enough slack to hook them together... So I put a large tiedown strap on the passenger side caliper ebrake, and frame, and cranked it down until the caliper ebrake spring on that side was fully compressed.
Now the 7" one is about 1/2" too short to fit... I took my dremel and removed just under 1/4" on each end mount of the cable and was able to just get it on.
Now the caliper ebrake arms are against the stop when the ebrake is released, and the spring is fully compressed when the ebrake is engaged... that will hold it.
Result is that a 7. 5" cable would probably do the trick... mine is actually a bit shorter than that, but much harder to install...
The attached picture shows the 8" (or is it the 9") cable next to a pair of pliers for size, and one of the two connectors that the cable ends hook to (so you can see what I am talking about).