Visit E-bay and plug in GL1800 Final Drive! You'll find numerous one for sale at reasonable prices
There's a Trike Shop located in Inverness Fl. which is technically in your back yard of Ocala Fl. The shop advertises they have 10 final drives on hand!
http://www.ebay.com/itm/HONDA-GOLDWI...5UWka-&vxp=mtr