Howay the lads, this may be a crucifiable offence, but does anyone have the low down on these?

I'm perversely taken with a Td6 L322 currently residing in my shed which is in need of a new gearbox and very little else, having had many thousands spent on it over the last few years. However my head is spinning after trying to research the rebuild of these boxes. They're underspecced, you need x valve body and y torque convertor, etc, etc... fuck knows.

I figure at least one of you must have made the plunge by now!!!

Cheers

Maybe but most of us own the earlier P38 with a ZF gearbox. I'm aware that the GM box fitted to the diesel L322 is only good for about 100k miles (the petrol version had a ZF which goes on forever). I've been speaking to a local owner of a 2006 with a failed gearbox at 115k despite it having been flushed and refilled about 30k miles ago.

Found this which looks to be a good step by step rebuild guide https://www.lrukforums.com/resources/gm-5l40-e-teardown.173/

this is the small amount of knowledge that i know about GM boxes. the numbers stand for 5l40e ,5l is the amount of gears ,eg 5 speed , the 40 is the amount of forward thrust the box will move eg 40 =4000lbs of weight the box will move forward. this is a small number and would be the reason that the boxes fail . a 4l60e is the box used for the early LS motors with the 60 being 6000lb of forward thrust and this can be increased up to 75 =7500lb and that's in a car , not a heavy 4wd. i imagine that the 40e can also be beefed up in the same manner. if you google 'how to rebuild a 5l40e gearbox' and watch the video.
PS the e stands for electronic.