Where do you plan on buying this from? Messicks/Coleman or local?  Either will be able to get you the right parts through the whole goods dept.  My L4740 looks like it has the same parts needed as yours.  I got the base (p/n L8335 aka TD170-98151) and a float valve (p/n L8309 aka (TD170-98161)).  You could get a non-float valve, instead (p/n L8308 aka (TD170-98171)).
I also got the second position kit (p/n L8336) and a second float valve for about $1,400-1,500 shipped.
All this info is on the illustrated parts website through Kubota: 
here, under the "OPTION" drop down in the T15000 and T15001 sections. There may be slightly different parts needed, depending on the year or version of your tractor, so have your S/N handy if you call a dealership.