Well, I took a punt and dropped by a local 4x4 wreckers. They had 3 WK's in stock, all of which had been gutted.
Checked under passenger seat of 1st one - cover was gone and so were the various 'black boxes'!
2nd one - cover had obviously been moved - no Transfer case control module either
Lucky last... passenger seat completely obstructing the cover (elec seat so couldn't move it!) Luckily someone had started to unbolt it so we pushed it up and BINGO!!... TCM still there and plugged in - checked part number.... same as mine!
Wreckers even let me plug it in to my WK to test before buying...All lights out and 4WD/traction control working normally
$195 total.. and great service.