Q: Can I fit any M42 screw mount lens to any Asahiflex camera?
A: No, Asahiflex cameras adopted an exclusive M37x1 screw mount, only allowing original Asahi Kogaku Takumar and independent Asahiflex compatible lenses to be coupled. Some early Takumar lenses for the Asahi Pentax (usually M42x1), were also produced in limited quantities in M37x1 screw mount.

Q: How can I distinguish Asahiflex models?
A: Like many vintage cameras, Asahiflex SLRSLR
Acronym of "Single Lens Reflex". See also "Reflex"'s are not marked with model designations. You can only identify different models by their specifications and details.
Asahiflex I (1952) has no slow speed dial, no instant-return mirror and only one non-standard sync socket.
Asahiflex IA (1953) has no slow speed dial, no instant-return mirror and two non-standard sync sockets.
Asahiflex IIB (1954) has no slow speed dial, features instant-return mirror and two standard sync sockets.
Asahiflex IIA (1955) features both slow speed dial on front and instant-return mirror.

Q: What are those Asahiflex cameras named Tower?
A: They were manufactured by Asahi Opt. Co. Ltd. for Sears, Roebuck and Co., an American mail order sales organization.

Q: Is there any book discussing Asahiflex cameras in deep?
A: The only one is Fred Sherfy's "Asahiflex and the Pre-1959 Asahi Pentax Cameras"