Vortex Sound Research

Just got a gorgeous new DX7 II-FD for Christmas. It sounds so good I can’t believe it. It didn’t come with a cartridge and I’m gonna get deep into sound design but don’t want to loose any of those gorgeous sounds it comes with. I’m looking for one online and was wondering if I can buy any DX7 cartridge or any DX cartridge at all for that matter. Are the preset sounds different across the models? Would other cartridges even fit or be readable?