It worries me that you would be speculatively chucking that much money at it, just hoping that the valve body is the issue. If at all possible, you’d be better getting the valve body tested first as a unit.

In case there’s any confusion regarding seals, both the GM 5L40-E transmission and the later ZF 6HP26 have rubber jump tubes that seal the hydraulic passages that pass between the casing and the valve body. For the ZF 5HP24, however, there are no rubber seals and it relies on the flatness & finish of the machined faces to provide a seal.


GM 5L40-E



ZF 6HP26



ZF 5HP24


Phil