You don't really provide enough information about your Willie Dinkins. Which census and where did you find him ? When and where was he born ? When and where did he die ?

I only found one possible match in the death index and I'm assuming this one is not yours :

Name: William V. Dinkins
SSN: 709-18-1974
Last Residence: 75225 Dallas, Dallas, Texas, United States of America
Born: 17 Jul 1891
Died: Jun 1982
State (Year) SSN issued: Railroad Board (Issued Through) (1951-1963 )

Here's a link to the Railroad Retirement Board in Chicago. Also, it looks like the Newberry Library in Chicago is planning to have a free seminar on researching railroad workers. You may want to contact the main organizer to see if the materials from the seminar will be made available thru the Newberry.

Railroad Ancestors featuring Paula Stuart-Warren
Friday, May 30, and Saturday, May 31 9:15 am – 3:00 pm
http://www.newberry.org/genealogy/genealogyevents.html#workshop