Patio door handle

I have a milgard patio door which was installed by the builder in 1995. The side of the patio door does not have a slot for locking mechanism which makes me believe it is a surface mount handle set. My neighbor sent me a picture of his handle set which is a surface mount handle set but a little smaller patio door compared to mine.
The door specialist took the measurements between the two hole opening it is as follows:
measurement is 5 - 3/16