What door thickness does this work on?

If you're looking for a surface mounted handle set, then I think you want to consider something like our 82-005. This has the latch built into the inner handle. Its hole spacing is 4-15/16". And I think there shouldn't be an issue with it working on a 3/4" thick door; it's when doors are unusually thick that things get a bit more iffy. The 82-055 has a latch that works inside the door frame, so I don't think it's going to work for you unless that was what originally was on your door. Take a look at the 82-005 instead and see what you think.