I don't have an XL, just the normal length flux.
For what it's worth though, I run SMC 2S LiPo's in mine. The old soft pack 9000mah and the newer hard case 7400mah. I use the side saddles though. Both of those packs fit in the side cases without issue. I didn't use whatever the stock cases used to hold them closed though, I used a velcro strap wrapped around the center. I got mine used and the original owner removed the stock latches.
When using the shorter packs, I put more foam in the front to hold the packs in place, but with the straps wrapped around the box, it kind of squeezed it so they didn't rattle around in there.
After extended use, the soft packs puff up a bit over the original measurements. Two of them stacked are 67mm. They are 156mm long including the wires laid flat and 45mm wide.
The 7200/7400 hard case 2S packs with 2 stacked are 52mm tall, 138mm long and 47mm wide.
I also had a pair of their 9500 extreme 2S packs and they were a bit thinner, 2 of them stacked were 57mm, 158mm long, 45mm wide.
I only ran those a couple times and tried using up my original 9000mah 2S packs I bought. After 16 months of running them in my brushless revo and savage flux, they were getting to the point that they were taking a long time to balance and the run time was starting to sag. One of the 4 actually dropped a cell, so I only have 1 matched (I ran them in pairs always) set of them. I kind of quit running them because of their weight. They were really hard on the brushless revo when jumping, so I opted to run the 7200/7400 hard case packs instead in all my trucks. They had a higher C rating anyway. However, I may deaden/get rid of the 9000 packs and perhaps use the 9500 packs at least in my outcast next year as the battery boxes don't need any changes to fit those instead of the 7200/7400 packs I'm currently running.
I was toying with the idea of running 6S, but I think I'll stick with 4S in my big trucks and just run 3S in my smaller ones.
