[kalnaren]

Different mechboxes fit into different guns, and sometimes function somewhat differently. Brief overview below (I haven't listed all the guns using them.. too many lol):

Version 1 - TM FA-MAS. High speed, high ROF, low torque. First Mechbox design, not used anymore. Very strong design. A stock TM FA-MAS will run forever. Highest rate of fire of any stock AEG (1,000 rounds per minute).

Version 1 Hybrid - L85. Most L85s have some kind of hybrid Version 1 mechbox. It seems that no two companies make an identical L85 mechbox.

Version 2 - M4/M16/MP5/G3. Free-floating motor. Non-reinforced V2 mechboxes can crack if the spring is too powerful. Don't use in winter if upgraded. Tons of parts available

Version 3 - AK/G36/AUG/MP5k/SIG. Strong design, thinner than V2. Tons of parts available.

Version 4 - Only used in the TM PSG-1. Pre-cocking design. After firing it cycles the mechbox so that trigger response is instant. Designed for semi-auto fire. Can handle very high FPS.

Version 5 - TM Uzi. Good stock mechbox, very limited after market support.

Version 6 - Thompson/P90. Very similar to the V3 in function and support. Larger mechbox, very easy to work on. Motor is fixed horizontally with the mechbox instead of vertically like many other designs.

Version 7 - M14 -Built for torque and high FPS applications. More difficult to work on, very limited after market support.

Version 8 - TM Type 89- Similar to the V2 but uses a mechanical 3-round burst function.

Version 9 - TM AK74/74U -Modified version 3 that includes a recoil function.

Version 10 - Modified V2 with recoil function. IIRC it also features cycle interrupt to stop firing when the mag is empty.

Higher numbers don't necessarily mean a "better" mechbox. A reinforced V2 will generally be as good as a V3, for example, and a V2, V3 and V6 don't really have much difference between them as far as function is concerned.

Like I said, the gun type is what determines which version of mechbox it has. If you're planning on playing a lot in the winter or doing a very high FPS application, you're better off with a gun that uses a V3 rather than a V2.

mechbox.com is an excellent site, but they appear to be down for a while. Check it out when it comes back up.