Mower Deck Question

[CVSB10JCS 9]

Starting tearing apart an old 48 inch deck I picked up somewhere and it has metal spacer rings between the spindle housing and the deck and the blades are "stepped" also! and it doesn't have the flat splined washer all my other deck have. I "think" the shell is the same but need to do some measurements on the two I have torn apart. Any ideas?

[CVSB10JCS 9]

found a really good older post that explains the different splined washer and gull wing blades!

[PhanDad 3,618]

The spacer rings were used when you replaced a "deep pocket" deck shell (such as used on mfg #1690271/2) with a replacement deck shell without the deep pockets. The "deep pocket" decks used flat blades. The rings and arbors were mounted under the replacement deck shell to lower the arbor to maintain the same relative location of the blade cutting line. The "gull wing" blades came with the newer splined arbor decks (such as mfg #1691218/9). Same splined arbor, but the new "gull wing" blade lowered the effective cutting line to the design location. In addition to the original purpose of the rings, I've seen them used above the deck to raise the effective cutting height of the deck. The most extreme raise I've seen is a non "deep pocket" deck shell with the ring and flat blades. Probably get an extra 1/2" cutting height. It's my understanding that if you do this, the quality of cut is effected since the amount of vacuum created to "pull" the grass up straight for cutting is compromised. (And the rock guard isn't at the correct vertical location either)For reference, the replacement deck install instructions: