same year trucks (66) different front springs?

[fleetman]

going to cut my front springs . i didnt want to cut trucks original springs so i picked up 2 from a board member locally- off of his 66.
when i saw his i knew they were shorter and beefier. so i have measured them.
pair A : 13 1/4 coil is 11/16 thick
pair B : 12 3/4 coil is 12/16 thick

can anyone explain how these stock springs can differ in the same model truck ?
i am wondering if i should just get some aftermarket drop springs ! because i have no idea how a 1 coil cut on A and B would compare in drop and ride characteristics !

any thoughts ! thanks