Re: Mercury serial numbers?? Home › Forum › Ask A Member › Mercury serial numbers?? › Re: Mercury serial numbers?? kerryUS Member - 1 Year (includes $3 online payment fee)Replies: 432Topics: 18 April 23, 2018 at 8:38 pm #74603 Direct Charge. I may be wrong, but I believe its half of an inline six. If you have too many, AND not enough, you're a collector.