Hyundai Repair: transmission issue, automatic transmission fluid, speedometer needle

Question
I have 2001 Santa Fe with (190,000 miles) and I keep the oil changed at regular intervals along with having the automatic transmission fluid flushed and replaced three times.  The other day I was slowly accelerating to about 30 mph and it appeared the transmission slipped out of gear. There was no warning or indication of imminent failure of any type.  No noises, no whining, no popping nothing other than it slipped out of gear.  Park and neutral are the only two gears working.  The stick shift slides into gear but D, 1st, and rev. all fail.  The check engine light DID NOT come on and the fluid (check at normal operating temp.) was red and clear with no sign of excessive wear.  I am baffled.  Two questions what do you think the problem is and if I rented a OBD II sensing unit and plugged it in would I get some useful information.  One other note the check engine light is does lite.

Answer
Chances are that the something has broken in the transmission (or transfer case if 4WD) requiring replacement (or overhaul) of the failed component.  If the speedometer needle moves when you attempt to accelerate, expect the problem to be in the transfer case.  If it doesn't, expect the problem to be in the transmission.

If your check engine lamp has not come on, it's unlikely you'll get useful information from the scanning the ECM and TCM, but you'll have no way of knowing this without attempting.