Garrett,
Send Dan Conley an email, he rebuilt my tail shaft on my S10 T5 transmission, changing it from electronic to mechanical.
Pretty sure Dan will be able to fix you up. This is his website:
http://t56cablespeedometer.com/email: cablespeedometer@yahoo.com
Dan can help you calculate the tire size vs gearing to determine the proper speedo gear that would best work. Will not be 100% accurate, but will get you close enough for rock and roll. There are different sets for S10 and/or GM, the TH350 has some that can be used for the S10 T5 also, as I recall.