I've got a Snap-On MT2500 scanner that I was using for my 91 SC that is no longer needed. I paid $350 for it used in 2008 and will sell it for $200 plus shipping. {SOLD}
I don't know of anything that can do much on the eec style connector cars. In a google search I only found one answer that seemed to work, it involves using a quarter horse. Other than that everything for the early systems is handheld devices such as the snap on mt2500, rotunda super star tester and OTC genesis systems. Still you will never get the data you do on a OBD1 or OBD2 compliant vehicle.
Alan
I have an Auto-Xray 5000 it is set up for both OBD I and II.
It's been great, I uses it on my '93 SC, '03 H2, and '99 F250. I have also on other peoples cars. Just so you know OBD I use car manfacturer specific plugs.
MikeH