The purpose of this occasional paper is to compare point estimates and trends included in the Monitoring the Future (MTF) Panel Study annual report: "National Data on Substance Use among Adults Ages 19 to 60, 1976-2021" prepared using historical post-stratification weights, with the same point estimates and trends obtained when using MTF age-specific panel analysis weights. The current report is organized into four sections: (1) Part 1: Overview of Old and New Weighting Methods; (2) Comparison Approach and Summary; (3) Differences Observed Between Old and New Weighting Approaches, by Substance; and (4) Updated Panel Report Figures and Tables. Evaluating the impact of the new MTF panel analysis weights on point estimates and trends reported in the MTF panel annual report for 1976-2021 indicates that, overall, 63.1% of all point estimate comparisons exhibited less than a |5%| mean change between weighting approaches. Further, no trend comparisons indicated a sign flip, and 87.1% were substantively unchanged in regards to trend significance. [For "National Data on Substance Use among Adults Ages 19 to 60, 1976-2021," see ED623992.]