Jeff,
Fortunately, Toyota started experimenting with electric speedometer setups while they were still using the right hand gear drive transfercase from '94-'95. What this means for you is that since you are planning on using a gear drive transfercase, all you have to do is wire in your speedometer directly into a '94-'95 style electric speedometer gear. Your trucks actual speedsensor is built into your factory speedometer, so once you drive the speedometer, the computer's speedsensor is set.
So you will want to search around for a transfercase electric speedometer gear from a '94-'95 4WD pickup.... and I want to say that they only came on V6 models (3.0l), Im pretty sure the 22R-E used a cable its whole life ('85-'95).
Here is the only picture I've got of the e-speedometer gears... The one on the right has a broken housing and a junk gear, and the other has a bad cap on it