Just wondering if there would be issues?

Don't see why not so long as it is a 17 size frame. You'll have a gap up front.

Yes, sorry it's a G4 G17 frame

Gen1-3 slide will work on a 4.  Gen4 only works on 4.

Yes and no.  Gen 2-3 slides will normally work fine on a Gen 4 frame.  There will be a gap around the front of the frame, but it'll still function fine.  However, with the 17L/24 there is an issue with using a Gen 3 guide rod with the Gen 4 frame.  What happens is if you put a complete 17L/24 upper on a Gen 4 lower the front of the guide rod will tilt up as you rack the slide and hit the inside of the frame, see picture below where the arrow is pointing.  When I tried this with the OEM Gen 3 guide rod I couldn't even fully rack the slide due to the guide rod hitting the slide.

I tried a Zev Gen 3 extended guide rod (extends flush with front of 34/35 slide) in this setup and it functioned 100% for a few hundred rounds.  But then I noticed the front of the guide rod was getting banged up and that's when I realized how it was hitting the inside of the slide so I stopped using this guide rod as I was worried eventually the slide might crack there.  I tested a Jager Gen 4 guide rod running it uncaptured without front screw on and this seemed to work just cycling the slide, but didn't want to risk it also hitting the slide so didn't try shooting it like this.

The issue with the Gen 3 guide rod is that the ledge on the inside of a Gen 4 frame where the back of the guide rod rests is wider on a Gen 4, so the back of the Gen 3 guide rod can move around more allowing it to tilt up more and hit the slide.

The only solution I found is a dedicated extra long 17L/24 guide rod.  I found one on the EE and it extends almost to the front of the 17L/24 slide.  However, I was only able to find the one and no one seems to make them anymore.  I've been emailing with Jager for a while now and Billy keeps promising to make a run of them, but hasn't yet.  

It will work, will need a gen1-3 rsa though, and you'll have a gap in the front

RSA?

Recoil spring assembly

The RSA= recoil spring assembly.

The post above (Russell), he refers to this a the guide rod. These terms
are usually used when referring to the RSA. <-- Glocks name for guide rod.

His post is right on. There was also a company in Germany making adjustable guide rods
from SS. Their very spendy.