crazyjr is right, the lightning 10 buggy center diff fits perfectly on the LS10. I know because I've owned both the buggy and LS10.
I liked the crt.5 diff better because its beefier
So, I found a much easier way to mount a crt.5 diff to the LS10. You'll need an extra diff mount and the 83mm dogbone. Just take off the front diff mount and attach another diff mount to it by screwing the two front mounts together through the brake screw holes. You can also add another screw if you're worried about flex but I found it worked just fine and was a perfect fit.
You'll still need the longer dog bone but you won't have to drill or measure any new holes on the chassis.