It seems like RV manufacturers love to use the flimsy aluminum extrusion-frame sliding windows, and the plastic sliding catches that hold them up are even cheaper. Our garage sliding door has those kind of windows, and the catches didn't even last a month, so I made replacement pieces for them. As you will see, the 3d object file is a combined left and right side. This should fit with minimal post-processing. However, I do print with a 0.8mm nozzle, so some nominal sizing may apply. 

To get these out, simply pop the plastic corner piece at each end of the extrusion loose, and the catch slides out. (I've also made a file for those corner pieces…) Don't lose the spring! 

I would strongly recommend printing this in PETG as it will be exposed to UV, and you should use 100% infill with >5 perimeters for strength.