Here is a solution to replace the antennae tube. It is made by BRP and you can purchase it from Tower Hobbies online: (http://www.brpracing.com/6977.html
I use this product without any issue. However, I'm running a high end FM transmitter (Futaba 3PK) with either FM or PCM recievers. When I've tucked my antennae inside my body using a cheaper FM transmitter (Futaba 3PD), I've had some glitching issues at the far ends of the track. I've never tried tucking the antennae inside the body using AM transmitters.
Just make sure if you use something like the BRP hideaway antennae mount that you don't cross the antennae over itself. The picture on BRP's website give you a good idea how to wrap the antennae.
You can also make your own antennae mount out of scrap lexan. However I prefer to save my time and just buy the BRP one.
Hope this info helps.