1984 – AAU, ABV, ABZ, ACZ, ADE, ADM, ADR, ADT, ADW, AEA, AEB, AEC, AEF, AEL, AEM, AEV, AEZ, AFA, AFJ, AFK, AFM
1985 – AAV, ACC, ACJ, ADA, ADP, ADZ, AEF, AEH, AEM, AER, AEW, AFB, AFK, AFL, AFN, AFR, AFS, AHA, AHB, AHC, AHJ, AHP, AHS, AHT, AHV, AJB, AJD, AJJ, AJH, ALA, ALB, ALC, ALU, ALV, ALW
1986 – ACE, ACV, AJC, AJD, AJN, AJS, AJT, AJW, AHC, AHU, AJS, ALW, ANA, ANB, ANF, ANK, ANN, ANP, AUB, AUC, AUH, AUM, AUU, AVC, AVT
1987 – AFL, AHC, AHV, ALC, ANK, ANN, ANR, ANS, AUC, AUK, AUV, AVA, AVB, AVN, AVV, AVY, AWD, AWE, AWF, AWP, AWT, AWU, AWW, AWY, AYE, AYF, AYL, AYW
1988 – AFZ, AWP, AYC, AYE, AYM, AYR, AYU, AYY, AWD, AZA, AZH, AZJ, AZE, AZL, BAF, BAN, BAP, BAR, BAS, BBA, BBF, BBH, BBN, BBT
Supica, Jim,Nahas, Richard. Standard Catalog of Smith & Wesson (Standard Catalog of Smith and Wesson) (Kindle Locations 17043-17050). F+W Media. Kindle Edition.
You'll notice "AFD" isn't listed and for 3-letter-prefix serial numbers, they're not in alphabetical/chronological order.
Calling S&W will result in the most precise answer.