About 440 S35s were built. From tank production #451, the design was to change to the S40 with the APX-1CE turret. Eighty of that tank design were to be built, while the ARL-2C turret manufacturability was developed. From tank #531, the design was to change again, to incorporate the ARL-2C turret instead.
Much as with the B tank family, the second version of the design family is bis. The third version would be ter, and so on.
The ARL-2C turret was a composite of welded plates, external grinding, machined castings in the gun mount area, and a cast cupola. As noted, the cupola design and manufacturing plan...and therefore the ability to manufacture turrets at production rate...had not been finalized as of June 1940. My understanding is that there still were ongoing discussions of rotatability vs. all-around vision features.
Idk, the historians from the GBM magazine article on it was rather confident that the turret was finished and would be introduced in July:
But maybe you have seen more recent findings? Also, I don't think any bis/ter designation was planned for the S40s with the new turret.
I have now finished P.M. Knight's Crusader book, which only reinforces the points I mentioned in my previous post on the subject.
Regarding some alternates on the tank, here is a table I made based on the info from the book about the evolution of Crusader armor since Mk II, with two proposals in orange:
The common feature of the two is the move in production to single plates instead of double or triple skin plates, which further improves actual protection at a low weight gain (odds are that the extra 300 pounds for the ultimate proposal compared to Mk III is because they thickened the armor even more, because moving to single plate usually changed immunity distance by 200 yards, not 500). This is what the Cromwell family eventually got, with only the turret still having double skin construction.
The book also notes that the 95mm howitzer was supposed to be used on Crusader III but in the end couldn't fit the two-man turret, and it confirms the Covenanter's suspension couldn't really handle extra weight while Crusader's could. These two points only strengthen the argument that the War Office should have accepted a greater weight limit within the 24 ton bridge to have slightly bigger Cruisers with less problems linked to excessive compactness.
I now have Solidworks so I will see if I can model both the Crusader II with straight front and BESA MG mentionned in the book, and a 21-22 ton Cruiser.