Can you mod R13 chassis to install R15 Dell 240mm AIO?

I don't know, but in my opinion it's pretty sad we have to ask that question in this day and age.

These systems should come standard with standard mounting for a 240 mm AIO. I guess it's one of those OEM decisions that were made at some point...

If it won't go up top, it will fit in the front with minimal mods (and an RTX 4080 Founders Edition)

photo from @Innovative313 

I am relatively optimistic because it seems R13 and R15 chassis use same oem metal skeleton. Dell just moved the 3.5” hdd cage at top of R13 to bottom of R15 probably to free up some room for top vent.  The AW bling of 240 mm cryo will still be preferable to third party hybrid alien.

It's possible, you'll just have to drill new holes for ventilation!!!

"The AW bling of 240 mm cryo will still be preferable to third party hybrid alien."

oooooh! I'm not sure about that

@aryuss Left is the OEM cooler, while this thread's initial series of pics earlier above shows the cooler w/ an odd (to me) top radiator portion w/ metal clips & a 'mounting frame' ... NZXT cooler's installed now so what happened, the OEM mounting frame transferred onto it so it could mount? I'm asking if that frame w/ clips is removable but I can about guess 

Totally removable. The left pic is at a different viewing angle, and the frame is not visible from either image.

The NZXT radiator is thicker than the OEM one and barely fits with the frame installed. You see no gap between the fans and the motherboard.

Dell engineering of radiator mount which is removable.  Instead of standard 4 corner screw mount of radiator, Dell uses clip on oem metal plate which adds bulk/thickness.  This clip on mechanism is used ubiquitously in chassis hardware.  Steve B scoffed at it in his review. I find it convenient for average user to unmount/remount radiator.  Not everyone is handy with screwdriver to mount radiator.  Ease of installation at the expense of simplicity or elegance.