MF135 Diff Preload

I have an MF135 and have replaced the crownwheel and pinion (Bare Co, same kit for short and long pinion), and all the associated bearings. Couldn't check the preload, the only shop here in Tassie that had the tool have lost the main part of it! Mechanics I spoke to said that the preload would only change if you changed the diff assembly, so I put it together using the same chip shield, or shim, behind the right hand bearing cup in the trumpet housing. Diff went in and was smooth turning, not too easy. When I put the pinion in I loosened the LH trumpet housing and noted that when trumpet had a 3 thou gap pinion and wheel were smooth turning and there was small amount of backlash, when trumpet tightened back up the pinion and diff are quite tight to turn (varies a bit from less than 10 to between 15 and 20 lb ft at the pinion), with no perceivable backlash and can feel every tooth. Anyone have any information or experience with new pinion and crownwheel and how tight it should be? I did set the pinion preload to 1.67 foot pounds using a balanced foot long rod with 758 grams on it (equal to 1.67 pounds). I thought I could remove the gasket on the RH trumpet housing and add another to the LH to move left it a couple of thou without altering the preload. I did take off the LH trumpet and tapped the bearing cup to ensure it was home, thought I may need to do the same with the RH housing to try to fix tight spots. Thanks for any input, ideas etc! Neil Mc