The book jigs do indeed show a 2mmspacer under the bush tubes
This is shown on page 60 fig 5.7 & again on page 62 fig 5.10 ( First edition of the book )
I made my own jig up to best suit the drawing on page 61, this clearly shows the 19mm tube sharing the same centreline as the bush tube !!
Lets round the bush tube up to 34mm ( 33.7mm ) rather than mess about with silly fractions of a mm
The bush tube centre will be 17mm
The centre of the 19mm tube will be 9.5 mm.
It can be seen that to keep both tubes aligned centraly a 7.5 mm spacer placed under the 19mm tube would be needed to keep all on a level plane as per drawing.
If you want to be a perfectionist a spacer plate of 7.35mm .
I have no idea as to why the 2mm spacer under the bush tubes is shown.
The 8mm spacer plate already brings the 19mm tube .5mm above centre. !!
As said. I made my own jig to suit the drawing & am happy that the upper wishbones are to the book spec.
I hope all of this double dutch makes some sense
