The Tamiya Leo gear boxes must be assembled, they are not pre-assembled like in the WWII kits.

Go here to order your Leopard parts direct from Tamiya USA, but you will need the part numbers from the parts list manual and kit instructions:

http://www.tamiyausa.com/contact/index.php

For Leo instructions: http://members.iinet.net.au/~wackywheelz/manuals/

Tamiya Info:

If I have to place a parts replacement order what do I need to do?

To allow our staff to process your order in a quick and efficient manner, it is extremely helpful when you are prepared with the part number that you are requesting. For R/C kits, the part numbers are located in the last few pages of the instruction manual. R/C kits have five and seven digit part numbers associated with them. Example: 53450 or 0005368. *Note: Many people often confuse the alphanumeric construction numbers, (MA4, MB17, etc.), with actual part numbers. Please use these numbers to find the five or seven-digit item number on the back page of you manual to expedite your order. For plastic model parts we first ask that you give us the item number of the kit. This number is located on the side of the box and in the front cover of the assembly manual. After giving our staff that item number, then we need to know the letter of the tree that you wish to purchase. Usually, plastic model kit parts trees are labeled A, B, C, D, E and so on.