the part i'm looking for looks like a sash tilt latch. They fit into the top of the stiles and seem to act like a guide and retracts for window removal. The sliders are approximately 38" x 60".
If it helps I.D. them, the wheels i found are P/N 87-188
The name on the locks is Pennco Inc.. vinyl sliding window.
let me know if you need any other info.