53 chevy 210

Hi folks, I've read alot of info from your site and have learned alot so I became a member. I am working on a 53 chevy 210 with my son and we need to put an axle seal on. He just bought this car a few months ago so we are trying to sort things out. The drive shaft has boneyard crayon markings indicating 57 chevy, but we aren't sure. I've been reading different forums and it sounds like this car had a torque tube axle originally? I don't know... I'm hoping you folks can share some knowledge and methods of identifying this axle and ideas on the seal. These numbers are on the third member 3707306 GM8. Thank you for any input. Regards, Rick