Skoda Gearbox Compatibility Code JDH

Hi,

Can someone help me pls? I am buying a 56 plate Skoda Octavia but without a gearbox. The gearbox code is a 5 speed JDH and I've read it is an 02J box.

I've struggled to find a JDH box and I'm wondering what box will be compatible to fit instead? Is there a guide for interchanging boxes? I've found this link but can't decipher what the gear ratios mean exactly? I'm not too bothered about fuel consumption being affected by the different box (unless overly excessive in a negative way).

The old box has been scrapped so I can't even get it reconned!

http://skoda.workshop-manuals.com/octavia-mk1/index.php?id=4348

Can someone help please?

Thanks,

Paul