If you take the time to read again, you will notice that walmart comment was not directed at you.

Okay some of the posters in this thread have received warnings, if you are not here to help with the question posted, then shut up and do not post. To those who are trying to help here, thanks.

To answer your questions, yes JG gearboxes are decent, but me being not very tech savvy with gear boxes, I'm not sure if it will fit. Although if it is Compatible with other China brands as you have said, that gearbox should work, provided you do what T7 said. Switch the selector plate to an mp5, or find a mp5 box.
Good luck!

Alright I placed the order from ebaybanned, I can start using my Mp5 AND my Hk516 Again

thanks ASC

My very first airsoft gun was a tippman I got when I was 16 I think, I kept it around and now pretty much the only thing left that's tippmann is the metal outer barrel. I also used a JG mechbox and am pleased with it. Mine was a v3 though, for an AK.

Tippman makes airsoft? I thought it was just RAP4

I'm the guy that put the v2 mechbox in the walmart M4 field duty kit by DPMS(PANTHER ARMS). It does fit, but it's tight...It was actually the mechbox from my well cqb bought from huang. The only problem I had so far is that on auto the screws that hold the motor plate on pulled out. I did get around 10 shots through my chrono before I tried auto, and it shot from 342-357 fps. LOL If you want pics, I'll take it apart and show you... and I still have the plastic gearbox that came with the M4...

It's alright, have you tried using thicker screws?

Your link didn't work... I bought that V2 DBoys. It is not such a grat deal for $50, instead, buy that complete JG V2 with motor from velocityarms, who has free shipping as well, for $99.99. The JG has a plastic cylinder head, mine came with a tappet plate that snapped when I tried to remove it, and I can almost guarentee a clearsoft motor will not pull a 400FPS spring, since a stock CA motor can't. But JG motors are actually pretty decent, and their mechboxes are Systema copies (or so I read).