'72, 5 lug Chevy van axles longer than a '72 c10 axle

[72timemachine]

I see a guy on CL has a real cheap '72 van rear end for sale, it's a 5 lug, my c10 has a 6 lug which I would like to swap over. The 6 lug is actually a '69 c10 rear end I have laying around and am considering using.

I understand I can buy new axles for just over 200 bucks but if the spline count and length are the same, can this be done?

Thanks for any help.