Replacement for a Trioving 5312B long plate lock

Replacement for a Trioving 5312B long plate lock required, we only want to replace the lock case is that possible or would we need to change the whole set up? Also what hand is this lock.

Hello that is a left hand lock.

The 5312B is obsolete and has been replaced by the 5312/8, it's identical but you'll need to change the handles at the same time because it uses an 8mm handle hub instead of 9mm. When you measure the door thickness for the handles don't forget to include the 2 spacer plates behind the escutcheons.