Rest in peace to these two legends, B.I.G. and Jay Dee. This gem is not a mash-up, but a real Dilla-produced song.

“Modern Day Gangstaz” (also known as “The Ugliest” and “Dangerous MC’s”), a song produced by Dilla featuring vocals from The Notorious B.I.G., Busta Rhymes, and Labba, appeared in its original form on a mixtape in the late ’90s, and eventually surfaced in full-length form in 2007. The new version, however, is a cut-and-paste job using the verses recorded for Biggie’s posthumous Born Again album, for which a new beat was used from Nottz.

Source: Wikipedia