That's also known as the "Tokuda Tower", which was a modification to allow use of a certain type of DRAM. I can't tell from your photo, but presumably they're LH64258 or similar other static column DRAMs.
You don't need that tower board fitted if you instead use TC514256 256kx4 DRAMs (or equivalent) that are more commonly used in the rev 6 A2000, and rev 6 and 8 A500s, etc.
