TLR 22

[Oh How Original]

Despite not liking them to begin with I'm really warming up to the TLR 22, I've seen one for sale that's mid motor but would prefer rear motor simply so I can run a normal stick LiPo pack rather than saddle packs.
Just wondering what's actually needed to convert from mid to rear motor? Is it like a little kit you buy or is it just separate parts?
Any help would be appreciated.