Can't help with this one, I made my front wishbone jig differently
I may help to point out that the jigs in the book are an example of how to make the part in question.
There are many ways of fabricating a jig
That said the book jigs are a good way of making the parts that are needing to be jig built & unless you have experience of fabricating jigs, I would reccommend that they are followed.
The critical parts of the jig are the 345mm width of the box section, this sets the width of the wishbone at the bush end.
The other critical measurement is the correct placement & fabrication of wishbone plate support. This is desribed in fig 5.4 This will ultimately set the
length of the wishbone.
The packing pieces are to ensure that the tube are held on the bush tube centerline prior to tack welding.
Personally, I feel that a jig becomes a lot more clearer once you have all the parts ready for assembly.
