Rebuilding diff and pinion height

So then, Yes something else I want to rebuild
So more questions and help needed
Basically I have a spare diff that has been in bits for the last 2 years and I want to rebuild it.
I have read if you're reusing the same crown wheel and pinion and using timken bearings again the pinion height and pre-load shimming will not need altering.
Which is all ok on this one, But I have a set of new 2.83 crown wheels and pinions that I will need to build up into diffs at some point soon.
Now these I suspect will need the shimming re-set.
So what I want to do is make sure I know how to do it and practice on this diff before I build my new ones up.

So I've been having a look about and LRT-54-503 pinion height block gets mentioned a lot and is apparently needed.
Is it necessary or is their another way of working the pinion height out?

This is my main concern at the moment but I'm sure their will be more confusion later

:bump: anyone
Had a little play today anyway, Went through a box of old bits and found what I thought was the shim out of this diff.
Put it in, Put the pinion in, Head bearing in and flange on. Tightened flange nut to speck and was very hard to turn by hand.

So I thought, Shim is too big or I've f*cked up.
Took shim out and put it back together, Flange now turns freely, But now need the correct sized shim.
I have 26thou of up and down movement now. But not knowing how much pre-load is needed on the bearings I can't buy a shim to suit.
Or is it easier to set up pinion height with (LRT-54-503 pinion height block)
Because I've spoke to a friend and he says he may have one he acquired
But I don't want to go look through all his crap if it's not needed

26 thou wouldnt seem right ,earlier pinions use two shims usually 60 ish thou plus a 7o ish thou shim, later just one 70 ish thou shim obviously they all vary but around figures i gave, you must set pinion bearing height before pinion bearing preload and without seal , shim already used as height is usually correct (i rarely find one that needs different height shim though obviously sometimes and more so with non timken bearings)also on pinion is often stamped correction height either plus or minus the nominal height

Ah, That's the problem, The shim I found may or may not be from this diff, It was stripped at least 2 years ago and stuff gets shifted about and lost
Seal not fitted yet.
Timken bearings have been fitted too.
The 26thou is with flange fitted, As I say I was just making sure it was the height that was making it tight.
So I'm thinking I have no option but to start again?
What is best way to set height from scratch?
As I say I have 2 aftermarket KAM 2.83 crown wheels and pinions to fit into casings at some point, And I was thinking these will definitely need resetting.
Unless your experiences of them differ, Would be easier all round if they went straight in.