It looks like you're opening up another can of worms there Mr Davis!!
And I thought it was a simple case of the larger diameter starter on older models and smaller version on later ones after a certain date.
The reason they may have continued using the very first starter on cheaper models was simply a way to use up excess inventory of it at the factory. Victa did funny things with wheels in the mid 70s like using the older type rear 8" wheels on the Victa 500 Twin and seeing some self propelled wheels on Victa VC Sports for example.

From the thread titled What About Now?
Originally Posted by Mr Davis
Hmm, there's a mower shop one town over that I used to pop into as a kid, they were a gold dealer back in the day, might be time I stuck m head in again... they had a couple of nice oldies on display too by memory... I'll take a camera!!
I think this older thread will be of interest in relation to this topic and what you said above.
https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/85219/1.html


Originally Posted by Tyler
MF, I have the same feelings for my grey 1990 Victa standard
Tyler that's it!! Looks nice.


Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!