6 lug on c10 Chevy.

[72timemachine]

I have a '69 long bed Custom c10, not sure what engine it had, only that it was a v8 with a manual transmission, this was not a 4x4, just 2 wheel drive.

Why is it that some c10's have 5 lug and some 6 lugs? Is the 6 lug a more heavy duty style of a c10 sort of what GM did in the 70's when they made the Big 10?

My other question is: Can my '72 disc brake spindles accept a 6 lug rotor? I was hoping to use the '69, 6 lug rear end in my '72 which has a blown rear end.

Thanks for any help.