I found all that....lone wolf doesn't offer that guide rod any longer.
My thinking is if a gen 5 19 and 17 have the same length guide rod, and a gen 3 19 slide fits a gen 5 19 frame why wouldn't the gen 3 19 guide rod work?
At work we have gen 5 47s and 19s. The slides are interchangeable. Those frames also take a gen 3 19 slide with no modification.