I have available a pair of seat brackets for Sparco bottom mount seats. I used these to install my milano 2's in my AT G35 coupe. One bracket is specific for G35 with AT pass side. The 350z driver bracket works in the G35 coupe without modification.
I do NOT know cross-compatibility with the G35 sedan, 6-speed coupes, etc. Two of the brackets are for a 6 speed 350z. As stated, the drivers side does fit the G coupe, so the pass 350z bracket may work in 6 speed models as well. PLEASE DO YOUR OWN HOMEWORK ON THIS! I will not be responsible if they don't fit...I only guarantee fitment in the G35 coupe.
That said, a new pair of these from Sparco, Wedge engineering, or planted tech would run you at least $280. I'm selling one pair for $160 shipped to CONUS. If you want all 3 brackets, you can have them for $200 shipped.