Thank you for the info. I measured as best as I could the part protruding from the front of the drill and found the internal thread diameter to be 7.94 mm and 1.0 mm pitch per thread.
I've a Bosch Scintilla SA drill, model #0 603 121 001, made in Switzerland which I cannot find any info on and also lacks the chuck. Other than that it runs great. Any info on this well made drill and where to obtain said chuck would be most appreciated.