There's been a couple of discussions on the uk sites about this, problems you will encounter with installing a 5 speed ZF is electronics, firstly there is no suitable shift mapping available (custom code required) for a diesel - the GM ecu won’t run the ZF. An interesting point that came up is in many peoples opinion the 5 speed ZF fitted to the early L322 (BMW) V8 is not as nice as a healthy GM box, and they are have their issues as well, just not as many.
Several of us here have been talking off line about the feasibility of sneaking the 6 speed ZF in, I can bore you with heaps of details but in short it’s not cost feasible, like the 5 speed it is possible but not feasible – and it all comes down to electronics.
So - no pressure Don, this is the first example I know of where someone has bitten the bullet and tried another solution besides the rebuild option mentioned in another thread (thanks Laurie/Gav). End of the day, this is what is needed, if your 5L50E will run off the existing ECU its game over. Shift point mapping can have mild tweaks for reasonable $, it gets expensive when you start from scratch.
Not sure I totally agree, I’m a big fan of ZF, but these anomalies are also a result of the software of the day - which the ZF shares the main functional logic. We are seeing a variety of problems from poor fluid / worn valves resulting in low pressure, worn / disintegrating clutch packs ect ect, and the software is trying to adapt to conditions that were never considered by the developers. These were the first truly adaptable shift map systems in a 4x4 and they are trying to adapt to situations that they shouldn’t be – the mechanical box failure is amplified by what the ECU is trying to do, and the software is the first of its type – far from perfect. It’s the Adaptive functionality that throws a lot of the variations; reset your adaptive values and your shift & lock-up points (behavior) change.
Disco2 ‘Adaptive’ or learning is limited to interactions with the engine ECU, the trans learns how to make the shift smoother through timing and variation of the Torque Reduction Request – that’s it - there's no change to shift or lock up points. Whole different ball game to what the early X5 was doing and unfortunately improvements to software have not been made available (X5 got them). But take a D3 for a drive; the software for the 6speed is a huge improvement.



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