Mine are, but those top ears on the diff cases snap off if I catch a sign pole or brick corner. Luckily, they're cheap to replace, just a lot of wrenching.
Overall, I'm glad I got them. Unless you can snag a used AE or Losi RTR here on RCT, it's the way to get started in rc trucking.
One of them got the front run over by a car/trailer in the street on it's maiden voyage and I think that all that I've got to replace is the shock tower and a shock cap and a couple screws - how cool is that? (Ummm...not the accident, though!!)
I'm sending the nimh setup to my bro, 'cuz it's new and will be perfect in his on-road TC4 and putting a mild brushless in it's place. I feel it's worth that upgrade.
One of these days, I'll post up my slop-reducing for the steering.
The receivers are on there pretty tight...are you sure it got tossed? Maybe you are having a hard time identifying it under the black top holder? If you'll post a pic, I can ID things for you.

Gene