[dfariswheel]

You have an extensively modified Colt Police Positive Special.
Some sort of adjustable rear sight has been roughly fitted to the frame. possibly a S&W sight.

The original barrel has been replaced with what appears to be a heavily modified Colt Python barrel, which has had the original markings replaced rather crudely.
The ejector rod head is missing, and the hammer spur has been cut off.

This is what it originally looked like..........

There's little value left after all the poorly done alterations, and it may not even be safe to fire.

 

[dfariswheel]

Good eyes.......... a close look does look like the rib is a separate piece attached to the barrel.
It looks like someone attempted to make a Diamondback out of a Police Positive Special.