In Morse Jim Strange was Morse's Chief Superintendent (not Chief Inspector, Morse was a Chief Inspector). Endeavour was a very good prequel in that included Strange as a contemporary of Morse, but he clearly was promoted more quickly. Also in Endeavour you may have noticed pathologist Dr Max DeBryn (catchphrase: "Gentlemen, shall we say 2 o'clock?"). He was the original pathologist in Morse. There was also a storyline in Endeavour which showed Morse suffering an ankle injury. Morse (John Thaw) walked with a peculiar limp which was a result of him breaking his ankle as a teenager.
One other thing (across "Endeavour", "Morse" and "Lewis"). Have you ever noticed how his bosses have always had "adjectives" for a surname? There was DCS Crisp (played by Trevor Harvey) in the pilot episode of Endeavour. CS Reginald Bright was in the remaining Episodes. CS Strange (James Grout) was in most episodes of Morse. CD Jean Innocent (Rebecca Front) was Lewis's original boss and she was replaced by CS Moody (Steve Toussant) in later episodes. So, Crisp, Bright, Strange, Innocent and Moody.
There were 33 episodes of Morse and 33 of Lewis. The cast of Lewis wanted to make no more than had been made of Morse.