How can I identify performance axle package?

[Beekeeper]

Hi guys, playing with the Challenger today trying to identify what it originally came with. It's an original unrestored 1970 RT but the build sheet and fender tag are gone. I know it's an original 4 spd car and did not get ordered with any of the comforts like PS or PB. I have verified it has a limited slip and I think it might be 3.55 but I can't be 100% on that. Unfortunately, the car had some front end damage at some point before I got it and the radiator support is no longer original so I don't know if it came with a 26" radiator.

My question is: is there a way to examine the leaf springs to determine if they are heavy duty? I read that the A36 package would have included heavy duty suspension. If mine is not, I can rule out the A36 option for good.

Thanks in advance for your helpful information!

[Chryco Psycho]

std springs are 4 each side , HP are 6/7 , if both wheels will turn evenly you cam mark the tire & count the number of rotations of the driveshaft to determine gear ratio but if the tires do not turn evenly the count will be out .