July, 2019.
Just completed, the "Argus C3 Universal," with a second lens mount, to accept 42mm screw mount lenses.
It is the second time that I have modified a C3 for 42mm lenses. My first one, the "Green Velour Monster" s/n 64942, has been a regular on my display tables at Argus Gatherings.
This new one was a "labor of love," for a good friend.

I started with C3 body s/n 1597394. The mount ring was in one of my spare parts bins. I can't remember what SLR it came from, it was a long time ago.
One tricky part was determining registration distance, back of lens to film plane... and then making sure that the calculations were correct after construction, with an assortment of lenses showing correct focus in film plane tests.
I made the screws that hold the camera face plate accessible so that it could come on and off while adjustments for the modification were made.
Red paint mark is for indexing the lens after mounting.
Notice that I left the original Argus threaded mount intact, so that Sandmar type lenses can still be mounted for use.
The standard 50mm Cintar f/3.5 will also fit, but with no distance markings on the lens itself, use of that lens is no longer practical.
Rangefinder still works, but when a 42mm threaded lens is mounted, the lower half of the rangefinder view cannot be seen.
Sunday the camera went with me into the field with a test roll of Kodak 200, using all three lenses pictured.
Our last surviving camera store in St. Louis area is going out of business. So the film was sent off to Parsons, Kansas, today. Results hopefully in a week a so.

Please click on thumbnails to see enlarged.
Thanks, Ed