I used the oil dipstick on my 62te (2010 T&C) and it worked great. I was having problems with shuddering and hard shifting. Drained the 5.5 quarts (by removing the pan), replaced the filter ($17.00 Autozone), cleaned the pan and magnet in the bottom of the pan, installed new gasket (included with filter purchase) and put in 5.5 quarts of Castrol ATF + 4. The total capacity on the 62te is 9 quarts, so I still had 3.5 quarts of the old fluid to get out of the system. I did this by disconnecting the transmission (return) cooling line that's on top of the transmission. It's the one closest to engine and under the exhaust pipe. It's a little bit of a challenge due to the confined space. To disconnect the line, remove the plastic cap by pulling straight up. Slide the platic cap up the tube to get it out of your way. Now there is a small spring clip in a groove near the top of the fitting. I used a very small screw driver to remove the clip. DO NOT LOOSE THE CLIP. Place a large rag around the fitting to catch the spring clip. Once the sping clip is off, simple pull straight up on the tube. Once tube is out of the fitting, replace the spring clip in the groove of the fitting. The tube has a taper, so when the time comes to insert it back into the fitting, you simply push down on the tube until it clicks into place. There is an o-ring inside the fitting that seals against the outside diameter of the tube. Ok, next I connected a flexible 3/8 inside diameter hose buy forcing it over the disconnected transmission line. I used 4 feet of 3/8 fuel line because it's what I had available. I used a 1 gallon clear jug and put the 3/8 hose into it. This gallon jug will be used to collect the remaining 3.5 gallons of old fluid. I had my wife start the van and immediately the old fluid started filling the 1 gallon jug. While the jug was filling, I was simultaneously pouring the new 3.5 quarts of fluid into the fill tube. When the fluid coming out of the hose turned a bright red (same color a the new fliud) I told my wife to turn off the van. I checked the level again with the oil dipstick and it was the same as when I started. I disconnected the 3/8 hose from the tube, pushed the tube back into the top of the transmission, pushed the plastic cap back down over the fitting and replaced the cap to the filler tube. Transmission shifts great and does not shudder.

 

I used the same method as you. I replaced both cooler lines because they were leaking. I had to take off the top radiator cover to get at the cooler side fittings. To check the fluid level I found the chart online, marked the engine oil dipstick every 10mm, and hooked up my HP Tuners software to get transmission temp. We just bought the van with 151000 miles and oil was brown and dirty looking. I thought it shifted good, but after changing the filter and all the fluid it shifts amazing.