Not sure what year your truck is, if it's a 2020 or newer with the towing prep (goose ball receptacle/pucks factory installed in bed), you don't need a slider. GM placed the attachment points further back starting in 2020, that with the rounded nose of the newer fifth wheels has made sliders unnecessary. There's several posts on this site concerning the GM trucks and this topic. I use a Reese Goosebox, I like it because of the clear bed and the ease of removing the ball vs the fifth wheel hitch. I pull my 31MB with a 2022 Chevrolet 2500HD, handles it fine. The 100 series is quite a bit lighter than the regular Reflection.
One comment though, I think the 100 series is similar to the 150 series in that it has a Curt turning point pin box. If that the case you can't change from it due to the frame size (the Turning point is all that fits that frame). If you want a fifth wheel hitch I recommend a B & W Companion. It's really a good set up. A lot of people use the Anderson hitch too, like Soundsailor recommends due to the weight savings.
Also, if your 2500 is one of the newer, taller ones you may find that it's hard to get a 100 series to tow level without raising the trailer (blocks on the axles). Again, it depends greatly on what year/height your truck is.
