New truck trying to figure out current suspension

[bmxbang]

Alright guys I just purchased this 71 C-10 and Im trying to get some insight on what drop it may or may not have on it. The front spindles look factory but not sure on the springs. The shocks where replaced at some point in its life front and rear. Tire size on the wheels are 275/55/20. I don't currently have measurements from the ground to the fender so I will apologize for that because I know it would help. The bed is off a 63 but im sure you could tell that!