The two former Pro Bowlers went in on Kelly in the latest episode of their "25 10 Show" podcast this week ... and one of the most serious issues they had with the coach was that it seemed he treated players differently based on race.

McCoy gave several examples to back his claim ... saying Kelly implemented rules that dampened the Black lifestyle on the team -- including music in the locker room and at practice, cars on game day, clothing and even how players wore their hair.

Shady and D-Jack both said Kelly would make comments about the tunes the players would listen to ... specifically saying he did not want to hear anything that included inappropriate words.

When it came to game day travel, McCoy felt Kelly took issue with the luxurious cars the players had ... so he'd tell them to use the bus to the stadium.

McCoy also recalled a conversation Kelly had with former teammate Roc Carmichael, who was told to cut his hair to look more "presentable."

But he suggests it was rare for Kelly to speak with Black star players on the team one-on-one ... as he usually delegated critical convos to assistant coaches.

As for the infamous Riley Cooper n-word scandal, Shady was upset with how Kelly handled the 2013 incident ... saying he knew his teammate was not racist, but Coach didn't let the players speak to the receiver about the matter.

McCoy and Jackson said they weren't alone in feeling that way ... as their white teammates also noticed Kelly's failure to connect with Black players.

There's plenty more -- Jackson also addressed the "coward-ass move" to release him following a report claiming he was connected to gang activity ... saying he was deprived of the opportunity to deny his involvement before getting the boot.