ask yourself this..
why would any decent gearbox builder have trouble assembling any gearset over any other ?
why would a manufacturer of a gearset claim people have had trouble because they didn't get the box built by themselves ?
ask yourself why its so much cheaper ready built and posted ?
the quality of maching is absolute shite, infact it was disgusting on the gears i've seen, you'd have to pay someone to clean it all up before they even put the box togther, there were issues with their rods aswell.
i dont use the guy but ring bernie (cts) and ask him what he thinks of them, he's done a few pars when people brought them the last time round