In my Haynes manual the specs at the start of suspension and steering chapter states as follows: 240Z: Front Coil Spring wire diameter 0.417 both sides, LH and RH. The free length states: LH is 14.1 and RH is 15.1.....If I am seeing this right then why a 1 inch difference in the length of front coil springs on a 240? Next to this it states a 260Z both sides are 15.5 inches long,  just saying. When I put my stuff under the front wheels a while back I saw this in the Haynes manual and got to checking my front springs. I put things back together as they came apart, does not make it right I know but I have a rear spring on the front left and not sure about the front right. Someone fuggered it up in the past. I have several extra OEM good springs so I'm thinking of taking both side apart and build with two springs of same length. Your thoughts???? Thanks

It's true. They are different. Driver weight compensation. Whether you notice a difference on 45+ year old springs, well, your experience my differ from others. 

Tanks zKars for the input. I think I'm gonna just take the left side apart on my car and get that rear spring out of there. The right side has the correct spring. I will build the left side with a spring like is now on the right. Right now when I push up and down on the front fenders one side is stiffer than the other and it has some height difference. All will work out well. Driver weight not an issue here. I weigh all of 135 lbs. Have to run around in the shower just to get wet ya know!!!!