how to determine what axle i need

[twillie2460]

To make a long story short I sent my rear 68 C10 axles off to a machine shop to have them re-drilled for 5X5. I never got my axles back and at this point they will never make it back. I however must replace these axles with new ones. When I look at getting a set and they want to know lenght, spline count and in somecases diameter all of which I dont know what my last alxes where as I never thought they were never coming back so I never knew these figures. My questions is how do I measure or do what ever I need to do to deteremine the correct axle lenght, spline and diameter so I can get these ordered to finish my rearend.