Modern Vespa

Sorry in advance for being long winded but I think it's a good story and could help others.
This new posting is a followup to these 2 previous postings.

Selector Box to Shim or not to Shim?

Gears as in a source for Large Frame VBB

I thought at first I solved the issue of the neutral clicking and jumping out of 4th gear with Jack 221's idea of the "cruciform rod has come unscrewed"
I removed the Selector Box and yes the Selector Rod had come unscrewed about a turn and a half.
I tightened it and re-bent the washer. That made it worse as I needed it to be longer. Then I had this great idea of taking my extra Selector Box and milling it 1.5 mm less. (I have a Bridgeport mill at work) I also bought 2 Selector Box shim kits to shim it out if I went too far with the milling.
With no shims and no gasket it was better, the clicking in neutral was less but 3rd gear was iffy and could not get it into 4th.
So back to the drawing board as they say.

I removed the engine and split the cases. Everything looked pretty good. The Cruciform had some light nicking.

I then decided to follow FINYoshi's idea 1995 Bajaj Chetak 125 - Budget Big-Block Build (Post 2571866)
Down the page about a third of the way.
I placed the gears that I had been using for the last few months on the shaft and marked the positions with a sharpie. I had another unknown set in a box. I choose what I though was the best gears to use a few months back. It very well could be a mash up of all different gears from who knows what Vespa. I have 2 4th gears, one with 42 teeth and one with 43 teeth. (this was a basket case with some double internal parts)

I removed the gears and assembled the cases together without any gasket or shims with both selector boxes.
I saw a shiny space on the selector box end of the drive shaft.

I thought it must be missing some sort of shim on the other end, I just need to space the drive shaft out a few milimeters. Who knows what scoot that shaft that really belongs to. Then I thought I should check the alignment with the Christmas tree. That looked fine and if I were to add a shim the gear alignment would be a problem.
So now what? Any ideas so far?

I removed the gears and assembled the cases together without any gasket or shims with both selector boxes. I peeked down the clutch hole and saw the Cruciform was barley contacting the inner gear cog area in the 4th position. Same for 3rd, 2nd and 1st. It was just touching 1st in the Neutral position, that was the clicking I was hearing.

I placed all my basket case, and used transmission parts on the bench and began to analyze the differences.
Everything looked normal to me except the old selector rod looked a bit different.

I decided to assemble the cases with the thicker, longer selector rod. Everything lined up perfect. I could benefit putting the shim behind 4th gear instead of on top of 1st. Any ideas on that?

After many hours of research, I had come to realize that there are Early and Late model Selector Rod's.
So I ordered the correct Selector Rod, new cruciform, crank seals and a gasket set. I am hoping to reassemble the Vespa next weekend. Riding this thing is my Nicotine.
I would never figured out what my issue was without the help of this forum. Thanks to all.

I forgot to add, what 4th gear does the forum think I should use. The 42 tooth with the protrusion or the 43 tooth with the flat shiny back?

Those are great shots and educational to boot.

Assemble 4th gear, the selector box and xmas tree into the case, then try your gear position. Looking through the clutch opening, you'll be able to see what's happening and help to see where the shims should go. Then you can add one gear at a time to continue checking. It's probably something of a compromise that will favour one or two gears over the others, but being able to actually see the difference a shim makes is a huge advantage.