Tekashi69 was in mortal danger just before he got arrested for racketeering charges, and the feds say they have the proof on tape.

The feds wiretapped several ex-members of Tekashi's crew and the transcript -- obtained by TMZ -- is pretty damming ... including a convo about "feeding" Tekashi after his appearance on "The Breakfast Club." Prosecutors believe "feed" means unloading bullets.

Play video content The Breakfast Club

One of the taps was on Jamel Jones -- gang name, Mel Murda -- a former member of 6ix9ine's inner circle, who is now behind bars.

During the convo, Jones says, "[Tekashi] is trying to dry snitch at the same time, homie. But he keep saying, f*** Treway, f*** that n****, Treyway. Ain't no n****, Treway. F*** Treway."

Tekashi's former manager Kifano Jordan, aka Shotti, responds with laughter and says, "Imma feed him though."

TMZ broke the story ... Tekashi was busted earlier this month on racketeering charges and prosecutors believed Tekashi was in danger of getting shot. The transcripts -- which refer to Tekashi by his birth name, Daniel Hernandez -- seem to graphically describe the danger.

Tekashi's former crew members were also recorded saying how Tekashi tried to separate himself from the Nine Trey Gangsta Bloods after firing his entire staff. The feds recorded an unnamed crew member saying, "That's cool. Now he gotta get violated."

Jones replied, "Yeah, super violated. Super duper. Ain't no much he could really do unless he run around with 100 armed securities all day."