So after making a thread on "how to figure out which speed sensor I need" on several sites, I didn't find any exact info on how to tell other than peak through the hole and count the teeth, which is a difficult task when the case is already on the truck... And which still didn't tell me whether or not mine took a mechanical one or an electric one, but in a few helpful threads, most seemed to think mine should take the electric one.
Soooo.... I made a crazy decision and just bought a random speed sensor on ebay. I found one marked as from a 98 4x4 4cyl A/T. It was marked as 11/32.
When I got it, first step was to see if it fit into the case--miraculously, it fit perfectly. Next step was to extend the wiring ~12 inches or so.
Once done and connected, I fired up the truck and took her for a spin and--Voila! I have a working speedo again!
Now just gotta figure out how close to actual speed it is getting me....
Also got the OEM rubber shift boot installed today as well.
-Ferg