From Alusq’s music installer:
//121 drum kit
VoiceDrum(MusicVoices,0x79,0x02231F0)
//122 drum kit (duplicate of 127)
VoiceDrum(MusicVoices,0x7a,0x0222FB0)
//123 drum kit
VoiceDrum(MusicVoices,0x7b,0x02226B0)
//124 drum kit (rock band-ish; recommended for if you have a modern-style constant drum beat in the background)
VoiceDrum(MusicVoices,0x7c,0x02228F0)
//125 white noise
VoiceDirect(MusicVoices,0x7d,0x3c,0x0516680,0x0,0x0,0x0,0xff,0x0,0xff,0xa0)
//126 applause (fun to use as a background-noise special effect at lower or higher pitches, but also used in stuff like the FE8 arena entrance theme)
VoiceDirect(MusicVoices,0x7e,0x3c,0x02AF0B0,0x0,0x0,0x0,0xff,0x0,0xff,0xa0)
//127 drum kit (marching band-ish; recommended for if your drums mostly play flourishes, like drum rolls and cymbals)
VoiceDrum(MusicVoices,0x7f,0x0222FB0)
If my counting hasn’t failed me, there seem to be 5 drumkits. They probably share some instruments. You should be able to find the samples in sappy if you change the voices address to one of the addresses in the VoiceDrum macro’s above.
Although this is the NIMAP2. Maybe vanilla FE8 uses more, Idk. I’d assume all samples are covered in these though.