B773A and D883A are the original numbers
you have to substitute a part, or buy the originals
For example, 2SB773 is often listed for B773A
and 2SD883 is often listed for D883A
See how it works? http/alltransistors.com/transistor.php?transistor=10881
http/alltransistors.com/transistor.php?transistor=20211