Sorry mate but there is no direct conversion from Xray for that purpose, HOWEVER it can be done but would prob cost atleast half the price of an 808e kit;(if not more IMOP)
For example you would from my knowlege require at least
1; 808e bottom deck
2; centre diff /motor mount , 2pce F & R
3;F & R centre drive shafts (as they are longer)
4; Battery & ESC mounting tray

you prob dont require the radio tray assembly BUT it would prob fit better ,

So at this point it's a fair amount of difference , The 808e is an amazing car kit & would like to see Xray come out with a conversion though it's not really cost effective...Good luck with your decision .

P.S , The 808e is worth the effort "TRUST ME"