Hi, I bought a 1990 Montero LS about, 5 months ago, and its the coolest ride ever. ( Ill post pics when i get a new camera ) Unfortunately, for about 3 weeks, in the morning as i'm driving to school, when it downshifts from 2nd to first it shifts HARD, and it feels like there is a bowling ball in my back seat. It does this the whole way to school, and not so much on the way back. I had the transmission fluid replaced, that didnt fix it. I took it to a transmission place, and they drove it and said they couldnt fine anything wrong, did a couple tests and found nothing, and that the compression on the transmission is fine too. I guess i could be very unlucky and it just isnt shifting improperly while they have it. Doesnt happen to them, but happens to me <img src="/forums/images/graemlins/frown.gif" alt="" />
Now, I know very little about cars, and was wondering if anyone could give me tips on anything else that could be causing it to shift so rough?

Not sure what could be wrong... how many miles on it? Any known history on the vehicle?

Has 193k miles on it. The car was very well taken care of. Im the third owner, the previous owner had it for 12 years and took it to the same mechanic all 12 years. Its never really been offroad. I talked to the mechanic, and he said the engine is still very strong.

Is it very cold there? maybe something to do with temp and fluid?

Check the following:

Driveshaft u joints
engine mounts
tranny mounts
tcase roll stopper (dside at the frame rail)
Throttle valve cable at the intake and tranny ends (broken or binding)