This may get complicated, but here goes...if you read all of it carefully, it's not hard or expensive. This is based on what I learned when researching for my project.
On the original truck, the VSS consisted of a 40-tooth metal ring called a reluctor ring pressed onto the output shaft of the transmission (or transfer case if 4WD). There was a sensor threaded into the tailhousing that would send a pulse every time a tooth on that ring passed, therefore it was sending 40 pulses per
revolution to a little electrical box called a DRAC. The DRAC then performed some operations on the signal and output it a couple different ways: one to the electronic speedometer, one to the antilock brakes, one to the cruise control, and one to the ECM. The ECM signal is the only one you would care about. The signal was dependent on the tire size and gear ratio of the particular truck it was in.
Option 1:
Now, you may want to just go the route I described above. You could either get a 4L80E or 4L60E transmission, or press a reluctor ring onto some other transmission and then drill and tap the tailhousing or transfer case housing to mount the sensor. That would give you a stock setup, but may be out of your reach mechanically or financially - I don't know.
Option 2:
Jags that Run (
www.jtrpublishing.com) also sells several different VSS's that simply screw inline with your mechanical speedo cable. You could get one of those, get a donor DRAC from the junkyard for $10, and tweak the DRAC to get the correct output pulsing (assuming you or a friend can do algebra and run a soldering iron).
Option 3:
Buy a 2 pulse per rev cable-driven VSS (part number 2PRS from JTR), screw it into your speedo cable output, and run the leads directly to the ECM. The pulsing rate won't be exactly right, but it will be pretty darn close and won't damage anything. For example, with the 2-ppr, 33-inch tires, and 3.73 gears, you would get 2279 pulses per mile into the ECM (instead of 2000). This way it wouldn't run any different than a new truck would if you put non-stock-sized tires on it and never reprogrammed the computer, and people do that all the time. $79 + 10 minutes labor and you'd be in business.
Option 4:
You could just ground out the Park/Neutral safety switch. The engine won't run optimally this way (no VSS), but it will run. I wouldn't recommend it for the long haul, but it's OK to get started.
I believe that the computer I am selling with the engine requires 2000 pulses per
mile. You could email/call the guy who runs
www.tbichips.com and he could probably tell you for sure - that's something I never got around to. The ECM service (part) number is 16147060.
