Geo, GE1445 has been the standard 18volt lamp for Lionel for decades. In the past it has always been rated for 18v. # 53 is rated for 14volts. I see some on Ebay call 1445 for 14 volts. The MTH whistle caboose would use a #57. Large dome, 14 volt like the #53.
But in reality, You could use a 57, 53, or a 1445, any would work fine.