The Martin Senour paint codes are correct. The problem everbody is running into is the prefix code (99L, 90T, ect) is an obsolete paint line. Martin Senour replaced that line about 5-6 years ago with Crossfire. I am actually surprised these old tints are being used as recently as they are. The color matching problem everyone is running into is NEW tints cannot sub in OLD mix formulas. The place mixing the paint should know this. The color code is the same (example: 3751 Meadow Green). 99L prefix code is old obsolete Acrylic Enamel.  This prefix on new numbers is also a price code, so not all Acrylic Enamel numbers, or Urethanes, will be the same prefix code.  When you get paint mixed at a NAPA store, tell them the color code (ex. 3751 Meadow Green), and what line, Synthetic Enamel, Acrylic Enamel, Urethane, or Basecoat, you want it mixed in. FYI, I restore Oliver tractors, most recent MS used @ 3 weeks ago.  Green is perfect match to originals and MS Clover White (4331) is EXACTLY like originals I have been around.