3656872 is the 1/2 ton axle used in 50'. Look at 41-55 1/2 ton 1st series at the link below.
http://chevy.oldcarmanualproject.com/1929_57chevyparts/57cmpc0522.htm

My 1/2 ton axle that I purchased has 3656872GM336 for the number.
I'm not sure what the "336" designates.

Last edited by randy luton; 02/04/2012 12:00 AM.

"Nothing astonishes men so much as common sense and plain dealing." - Ralph Waldo Emerson