4F27E / FNR5 Adjustable Band Pin & Nut Problem Solvers Complaint: Slips after build on either 1-2 shift or 3-4 shift or burns band and / or drum or slips / flairs on 5-4-3 or 4-3 downshift.Cause: Unable to adjust band as no provision exists except to buy expensive gauge tool and 5 different preset length bolts.Superior Correction / FIX: The fix is to install the K0121 and simply adjust the band following our easy step by step instructions. The new adjuster and locknut allow you infinite adjustments without tools or extra parts you won’t use.