Looking for replacement tilt latches
The window latch has the below markings on the bottom.
Apart from the numbers has the Alphabet J.
Pat.#5.139.291
375
J
Please suggest what the 375 and "J" stand for and Could you please suggest a replacement part.
Sure! The only relevant difference between the 26-419 and 26-243 is the position of the bottom locking "tooth." This is shown in the diagrams below: the 26-419 tooth is 3/8" from the front of the housing, while the 26-243 tooth is only 3/16".
That said, there is a high chance that neither tooth aligns with your original. In my experience that doesn't really matter all that much. The only function this tooth serves is to "snap" the latch into the slot and keep it in place. However, when the sash is put back in the frame and is ready for operation, the latches are fully braced against the side frame of the window anyway. It's not like they're going anywhere.
All that is to say that it's good to aim for an exact match when it comes to this kind of latch, but if that bottom tooth position ends up not lining up with your original then it's still usable.