From what i understand many of the t-rex parts are interchangable with the MX 400. Does anybody know what parts are not? Also what heli would be the better beginer heli, when cost is a problem.

Trex's are great heli's for sure, but check out the Esky Belt Cp. You can get a RTF for $180 and they're getting pretty good reviews.

Most of the Trex parts are interchangable with that heli also.

The T-rex and and MX-400 were designed by the same guy, Li Chann. Many parts are interchangeable, but I can't give you a list here. If you search runryder.com or x-400tuning.com or trextuning.com you will find lists of interchangeable parts.

If you are a beginner the MX-400 is much more stable and the aluminum frame tends to be more durable. That said, the T-Rex has a greatly improved tail rotor slider and blade grips, and more options on blades, etc. You can greatly improve the stability of the T-Rex by placing large wheel collars on the flybar out next to the paddles.

My X-400 has many T-rex parts, including the T-rex blade grips, tail slider and blade grips, extended boom, and many others I can't remember at this time. I also have the X-400 CCPM kit with metal swashplate, metal tail gearbox, boom-mounted digital tail servo, etc. It is super-stable, almost as stable as my Raptor 30, and far better than the Piccolo-type helis I had before.

If you want amazing deals on parts for the X-400/MX-400 send me a PM and I will send you an email address of the guy I buy from. His prices are untouchable and I don't feel comfortable posting his contact info on a forum.

I haven't seen the E-Sky helis recently but they are far better than they were a few years ago. If they have a belt-drive heli I am sure it is nice and smooth. Just make sure you can get parts!

**EDIT**
I just realized Helidirect carries the E-Sky Belt CP. What a great-looking heli! And Helidirect is in Malden, Mass so parts should be easily available. Thanks for the heads-up on that one Jeeum.

I've got the CF version and have only hovered it in the garage so far, so I can't give a really accurate description of how it flies but I'm happy with it so far.