All,
This Sonnax diagram has all of the upgrades available for our 545RFE transmissions, for the valve body and pump. This far exceeds what Transgo has provided in the past, but the 545RFE has been out for 18 years now and they've had nearly 2 decades to analyze the design deficiencies and provide upgraded parts. IMO, all of them should be done when rebuilding the transmission, as this addresses the early wear points in the valve and pump body bores.

The pictures have the Sonnax part numbers next to each upgrade part. If this upgrade is part of a rebuild and a Magnefine filter is added to the system on the cooler return circuit, it should help tremendously. If the Sonnax upgrade parts alone added $200 to the rebuild, it's still peanuts compared to an unwanted early rebuild due to failures in one of these hydraulic areas. Several of these valves (PR, CCV switch valve, etc) can destroy both the TC and the clutch plates in very short order if they stick in an unbalanced condition for even a brief period of time.

The TC clutch release depends on balanced fluid flow on both sides of its apply piston, in order not to lock up or drag and it also depends on a non blocked cooler flow return line to keep the pressure from going berserk. All of that is controlled by the valve body and pump valves. It turns out that if the cooler return filter is blocked, the bypass relief valve in the transmission can't function because it’s after the fluid return filter and will starve the internals for lubrication, as well as pressurize the TC to where it can't disengage. Cascade failures are a blocked cooler flow and overheated/burnt fluid.

In retrospect, it would have been far better if the cooler return filter had been located on the outside of the 545RFE - would have facilitated 12,000 mile/annual maintenance changes with very little effort. A Chrysler transmission engineer stated that they're seeing more and more failures due to this filter clogging and blocking fluid return flow, which causes a catastrophic cascade failure effect internally, all because a $20 filter can't be accessed easily enough. Most people would gladly change a $20 filter once a year, but not if it's part of a $250 - $300 fluid and drop the pan filter change.

Sonnax even has a larger clutch drum with 20% more torque holding capacity for the (5)45RFE, reminds me of what Ron Wolverton of SunCoast showed me for his $10,000 68RFE top of the line rebuild.