For pity's sake - will somebody just LOOK at the blasted thing to see if it's zinc or brass?
Zinc is "silver"/gray; brass is "gold". File the paint off; look at the broken end - what color is it?
Modern die-cast locos are covered in brass detail. But some is zinc.
Just look at it; much more effective than the verbiage of "debate".
Silver/gray = no solder. Gold = solder your heart out.