Out of balance Autostick gearbox

[bobbywil]

Can anybody explain what would make a gearbox vibrate .I am putting an Autostick box on the rear of a Subaru for a motor trike and the Mechanic cannot stop a vibration in the assembly when running . The engine on its own runs beautifully . I would like to use the box as i have two of them and dont want to waste them as well as thinking they are Great Any ideas would be appreciated