The Snap-on Reverse Input Drum Seal Sizer, No. RIDS970, helps insure proper seal installation in popular GM transmissions. By using the RIDS970 for tricky installation of reverse input drum and over stator shaft is simplified by pre-shaping the Teflon seal with this special seal-sizing tool. This sizer works on GM transmissions from 1982 to present, including 4L60, 4L60-E and 4L65-E automatic transmissions.