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1991 4L80E 2004 5.3 Compatability problem
I have a 91 Suburban 2500 that came with a 4L80E. I just finished up the 5.3 swap. The 5.3 had a 4L60E attached so I had to repin the harness and segment swap (from another 04 with a 6.0). Truck runs great but shifts like crap. I did the Bluecat tune and it helped with the shift point but not the neck breaking 2nd gear shift or the ridiculous downshifts when you roll on the throttle a little to aggressive. I've been reading the Force motor is different in these older trans? I have no Idea what that means or how to fix it. Do I need to change internals to bring the transmission up to par with my PCM or can I fixit in software?