I'm going to attempt to make a firetruck cake for my nephews 3rd birthday. Does anybody know where I can get a working siren for it? Does anybody have any templates on cutting the cake for the firetruck? Thank you in advance! God Bless you!

Don't know about a siren but here's a truck I did that is very simple to make:  https://www.cakecentral.com/gallery/i/1302773/simple-firetruck

You don't even need a long loaf pan - just a sheet cake cut in 1/2 long ways and stacked then a mini loaf cake on top at the front :)  Or for the front maybe cut some off the 'loaf' cake and add to the front.  That would shorten the finished truck but could work it you don't have/want to buy a mini loaf but if your sheet pan is 12x18 it would work.  Just cut 3" or 4" from one end

Thank you so much for your help!