You're using a 2N5401YBU PNP transistor manufactured by ON Semiconductor in your design. A good drop-in replacement for this PNP transistor is the BC556B manufactured by NXP Semiconductors or Fairchild Semiconductor.

Here are the key specifications for the BC556B:

Please check the datasheet to make sure it fits the requirements needed for your design. The actual replacement might depend on the specific requirements of your circuit. Keep in mind that each transistor model has its own unique characteristics that can influence circuit performance.

Also remember to verify the package type of BC556B to make sure it matches with your current PCB layout. If it doesn't, you may need to adjust your layout or look for another replacement.