What could be wrong with my Dodge transmission?

I have a 99 Dodge Ram 1500 Quad Cab 4x4. It has over 100,000 miles on it. The transmission has been acting funny for awhile now, but it has recently taken a turn for the worst. For awhile it would be a delayed shift between 1st & 2nd & 2nd & 3rd, but once it shifted it would go up to speed just fine. A few days ago, we noticed the 'overdrive off' light was coming on after driving it for awhile. Last night coming home my husband was driving it fine at 70 mph and all of sudden he lost every gear down to 1st. He limped it home at 25 mph and dropped it off at the transmission shop.
The transmission shop checked it out today and this is what they said: the fluid is dirty, but it didn't come up with a code on their scanner.
Any ideas? Is this something my husband (who is very mechanically inclined) can rebuild himself (with the aid of the service manual)? Or do we have to take it to a shop?

Thanks!!!!

If you have been having problems for "awhile" , then chances are you will need a rebuild. What you should have done to verify this is to drain the fluid and check for yourself. If the fluid looks or smells burnt and you see metallic particles in it, then a rebuild is required.

As stated above, the automatic transmission is a highly sophisticated unit which requires special tools and training. Usually, this is beyond the scope of the home mechanic even if he is experienced.

How many times have U changed the fluid & filter ?

Well.....did they change the fluid and is the problem still there??

I am mechanically inclined too, but will not touch an automatic transmission. you need presses, and measuring equipment that I do not have. If your husband has everything, then he is certainly welcome to try. the transmission is electronically shifted instead of fluid pressure changing gears like int he older trannys. the clutches are still shifted by fluid along with the bands. if it were an electrical problem, there shoud have been a code. if it is a clutch problem, the entire tranny needs to be disassembled. it will take time for a shadetree mechanic. I would just take it in to a shop. Good luck!

you can change the oil and filter yourself, but I can't even rebuild an automatic transmission. More than likely, when he drains the oil, he's going to find alot of metal shavings inside. If the transmission isn't messed up, this is normal to an extent. First of all, though, check to make sure you have good vacuum to modulator valve. Sometimes you have a vaccuunm leak, and they tell you things like the oil needs changing or the transmission is messed up. And all it has is a loose or cracked rubber hose so you are losing vacuum.

If they said the only thing that is wrong is that the fluid is dirty you probably need the fluid and filters changed for the tranny. Be sure to either use Mopar ATF+4 or Amsoil Universal ATF (which meets ATF+4 specs). Some rebuild kits that replace the bands on these transmissions are relatively simple to install. It sounds like your husband could probably do it himself.

I experienced the same problem a while ago with different type manufacturer.I drained the oil and refilled with new transmission oil and everything was just fine.Remember to check transmission oil level with engine running.