Wrong transmission fluid

Well it looks like I blew it! I put 90w gear oil in a ranger 5 speed manual transmission.
A few months ago we had to change out the clutch parts (Flywheel, pressure plate, clutch, clutch actuator assembly, etc) - when we dropped the tranny to do this - it looked like it had 90 gear oil in it so we refilled it with the same ( about 2.5 quarts - it was almost empty - from draining while changing the clutch)
Anyway, I've put several thousand miles on it.
I just got back from a 900 mile trip and when we got off the highway and I down shifted - it started making a strange noise like a dry bearing. I checked the fluid tonight and it is low..
I also did some further research and it turns out the it is susposed to have Dextron fluid in it.
oops What have I done ??
What damage have I done by putting the wrong fluid in it ??
I am what you would consider an advanced backyard mechanic. It has been years since I've overhauled a manual transmission, but have overhauled many motors over the last 20 years or so.. Anyway, am I gonna have to tear the transmission down for overhaul as a result of the gross error ??

:mad:

Thanks in advance for any assistance in this matter

i would just get a new tranny. sance you said that you heared a dry buring noise. then i wouldn't trust that one again.

same thing happened to me. after the whining starts, u got about 2 weeks