My 2017 4x4 door jamb spring code "SSAA" (front GAWR 3450lbs). I have 85,000 miles.
I just bought adjustable Bilstein 5100's front and rear (used 10,000 miles). The seller took off his Bilsteins and stock coils and put on Fox with coils.
His 2017 4x4 spring code is "22AA" (front GAWR 3375lbs). He has 115,000 miles.
Both trucks have the same rear GAWR.

What is the difference between his front springs and my front springs?
I've heard about "sag" but I don't know how to tell if I have that?
I'm trying to determine whose springs I should use?
Using the opportunity to learn more about suspension.

I'm searching, there are threads, but it can get hard to follow and I'm not sure I'm reading some of the information correctly. Hoping someone can spoon-feed me a more direct answer. or at least a better direction where I can figure it out. I assume my springs might be heavier than his and newer so should I use mine?

 

These seem like safer and easier to use spring compressors than the two clamp style cheapies.

I’m going to swap springs and make the setting less than 2.1 inches.