Last year I noticed that my tranny was slipping. I checked the vacuum lines from the fuel rail and throttle body that are connected to the modulator on the 4T60E and noticed that there was tranny fluid in the lines.

The tranny fluid was also low but there were no visible leaks on the floor of the garage. While inspecting the vacuum lines the rubber T connector on the throttle body crumbled and I was off to Advance auto parts to find some new connectors. I purchased a plastic T connector with two 3/8” and one ¼” port, a 3/8” to ¼” plastic adapter for the modulator connection, a ¼” to 3/16” plastic adapter for the fuel rail, two feet of ¼” fuel line for the modulator, one foot of 3/8 fuel line for the throttle body connection, one foot of 3/16 fuel line for the fuel rail connection, four quarts of Castrol ATF Dex III and a new Delco vacuum modulator 8662967.

I have been driving for over a year now with no problems.