Industry leader in hydrants - been around for many many years.

http://www.woodfordmfg.com/

http://www.woodfordmfg.com/Woodford/WFDhome.htm

Can't help with your problem, but a call to woodford and a expert will tell you quickly what you need  . . .

If it needs replacing, here is a add on product, that makes repair or replacement of hydrants a more pleasant job - http://www.seppmannenterprises.com/