I spent some time under the truck the other day and measured what I could. Here's what I saw.
The front spring on the new 2019 is quite a bit shorter (thinking this was done to take some mass out of the assy, partly adding up to the 200# mass reduction on the 2019), which makes the perch on the strut that much higher. Without having both strut assys out of the truck and in front of me, I can't say whether the overall length of the assy is the same. If they are the same overall length and all mounting points are the same, you could theoretically use a 4th gen strut assy with lowering springs on the 5th gen.
Seeing that I want to improve the ride quality when lowered over what I experienced on the 4th gen Ground Force kit...I just decided to wait for the Inez 3/5 4x4 kit to be released. It just isn't worth the time trying to see if the 4th gen ground force kit will work on the 5th gen, if I want to go in another direction anyways. Also, I don't have the upper strut mounting assy for a 4th gen to be able to compare them.
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