If you check the AGCO parts site
www.agcopartsbooks.com/PartsBooksN
look under the White FIELD BOSS 16 TRACTOR.
At the bottom of the field boss list of components is the
loader valve and hoses. There is a manifold and
the part number is 33-0082856. If you can find
a Massey Ferguson dealer in your area they
use AGCO for parts. You could check to see if they
can order that manifold for you if that
one would work.
Also the White Field Boss is made by Iseki and is close to
a TX1300F. That is where I got many parts for my TX1300F.
The Massey Ferguson 1120 tractor is also an Iseki
and a variation of the TX1300F