Hello,

 I am also looking for a rollbar for a 1555, as well as for a 1655, 1755 and 1955.  I have talked to Laurin Inc. and they make one that will fit.  I think they were somewhere between $1,200.00 to $1,500.00 in US dollars.
I did not get one from them so I cannot comment on the quality, etc.  I just know they make them.  One thing to be aware of is that they only sell to dealers so you may need to get your local AGCO, etc dealer to order it for you.

Joe G



Laurin Inc. 
(514) 689-1962
487 Principale Street
Laval, Quebec  H7X
Canada