1999 Chevrolet Tahoe transmission

Overfilling a transmission can be bad.

Let the transmission cool down and drain some of the fluid and retest if it works.

The transmission fluid was between the full and low dots on the dip stick before this issue. Now it is very over full. Have had no issues with the trans before this. Many other problems but this is the first for the trans.

Not sure if this would matter but was driving on a snowy slushy highway when this happened.

What is the color of the transmission fluid?
When transmission fluid heats up, it would increase in level.

Kind of a dark red to light brown. Found that today there is even more fluid in it then there was yesterday when it first broke down. Seems very watery as well, literally drips off the dip stick quickly.

Also found that the transfer case will engage my 4WD low in any gear including park where it would on shift to 4WD low in neutral.

There is a possibility the transfer case has failed so you need to investigate further.

I pulled the pan off the transmission and it was clean. Some sludge on the magnet but nothing terrible. Filter seemed unusually heavy when I pulled it off. Was wondering if a torque converter failure is a likely problem before I pull the whole trans.

Check the filter to see if it is clogged not allowing transmission fluid to flow through. I have encountered situations whereby the filter element is dislodged and blocks the fluid passages.

Update to my transmission issues. I finally have everything apart and pulled the torque converter to replace it. When I went to install the new one I looked in for the ears on the front pump, I found there were none. Upon further investigation I saw pieces of the front pump gear laying in the hole. Now I have to find the parts to rebuild the front pump. Seems auto parts stores around me don't even know what I am talking about let alone have the parts.

I believe you are referring to the oil pump.