Nardlyfe30

Did you ever find a solution to this issue? I have a similar issue with my 2011 gmc sierra 5.3 with 166k and same rear gear ratio but recently mine seems to slip or not fully engage when manually shifting from 1st to 2nd with heavy acceleration but shifts just fine in drive under the same heavy acceleration i like how it shifts quicker when i manually shift it verses when its in drive or i wouldn't worry about it i also would like to fix the issue now or try something to prevent a big issue in the future. If theres any suggestions or fix i would appreciate it