Here is my Caster F8T conversion with a 1717 motor. It was a tight fit and I had to use an EliteRC motor mount and also shave down the steering post to provide enough space. Not pictured is a top plate I made to link the front bulkhead to the center diff to prevent chassis flex that would cause the steering post to hit the motor.
I've since sold the 1717 and I ordered 1518 to replace it. It was just too much motor in weight mostly. I would have kept it, but couldn't see a use for it in the near future.
Pics can be seen in this post.
http://www.rc-monster.com/forum/showthread.php?t=28552
Here is a video of it on the track running on 4S. It was literally my first run with the truck.
http://www.youtube.com/watch?v=y4CV2k60svE
ben