You have a mix of clutch discs. The loader (955) used the bronze metallic and plain steel discs totaling 22 per side. The older D4's with organic and steel discs used the 16. The current available combination of metallic and steel is 12 and 12 and total a thickness of 3.480 in.
The old recommended new thickness total was 3-7/16 inches but you can run a stack as high as 3-5/8 in maximum. I would still check to make sure the clutch springs are not bottomed out if you run the maximum thickness.