1973 Firebird Cowl Tag Info

A table of 1973 Firebird cowltags showing the rivets/screws change date. 
Trying to narrow it down.

Appears like somewhere in the N130xxx to N131xxx area it changed.
All seem to be 04C, but the ship dates are quite off on some.
Not sure of the reason for that.

Started tracking the Ident. # from the PHS to see what it may lead to.
VIN Body # Date Unk FastenerComments
N1003xx 007913 10C 030430 rivet HFR; Formula, ship date 11-01-72; BS: 10-25
N100479 008430 10D 040343 rivet Formula
N100719 019816 10C 703214 rivet PHS: 11-2-72
N101721 ???990 11A 100652 rivet
N102818 005387 11B 150213 rivet
N103014 007846 11B 160423 rivet
N1 008927 10E 070343 rivet Formula
N103550 013859 11C 200515 rivet
N103986 014696 11D 220562 rivet
N105258 023326 12D 280853 rivet
N105476 024157 12D 300049 rivet
N105692 024193 12B 300709 rivet
N106110 025490 12B xx6701 rivet
N106915 025051 12B 350858 rivet
N1xxxxx 026071 12B 300289 rivet Formula
N1xxxxx 031492 12C 390364 rivet TA
N107670 031556 12C 380738 rivet TA
N1xxxxx 01A 480261 rivet Formula PHS: 1-9-73
N1xxxxx 041140 01A 480721 rivet Formula
N110584 040968 01A 490045 rivet
N1xxxxx 049307 01B 520886 rivet Formula
N1xxxxx 049712 01B 550464 rivet Formula
N111702 745746 01B 525844 rivet
N112029 049625 01B 540068 rivet TA
N112507 051294 01B 550683 rivet
N112820 052429 01B 560824 rivet
N112858 052808 01B 570018 rivet
N113870 053050 01B 600635 rivet
N114255 053166 01B 610964 rivet
N1xxxxx 01D 620419 rivet PHS: 1-30-73
N1xxxxx 054400 07B xx0325 rivet Navajo Orange Formula
N1xxxxx 055990 01D 620344 rivet Macho Poncho Formula
N114693 057640 01D 630448 rivet Navajo Orange Formula
N115283 rivet
N115552 058816 02D 080634 rivet Esprit
N115961 059503 01E 630202 rivet Formula
N116018 058749 01E 680385 rivet
N116197 057785 01D 650217 rivet
N1xxxxx 058776 01D 660853 rivet Formula
N117569 055369 02A 730973 rivet
N1xxxxx 063161 02A 720031 rivet Formula
N1xxxxx 064710 02A 720661 rivet Formula
N118255 066695 02A 760295 rivet TA
N120018 071417 02D 820712 rivet
N1xxxxx 076465 02D 820562 rivet Esprit
N120826 078517 02D 850673 rivet
N1xxxxx 078465 02D 820562 rivet Esprit
N121647 082061 03B 900157 rivet
N122024 082862 03B 920307 rivet
N122646 084602 03B 950713 rivet
N1231xx 03B 980257 rivet PY transamric
N123238 086806 03B 980537 rivet Formula; PY Importsmasher
N123211 08860? 03B 980429 rivet
N12352208203703B990829rivetW66; HFR
N124156 091550 03D 030565 rivet
N124449 095997 03D 050077 rivet PY; hojs69
N124943 097214 03D 070249 rivet
N125163 092651 03D 080305 rivet
N125314 097040 03E 090097 rivet TA
N1xxxxx 098413 03E 090653 rivet Navajo Orange
N125478 100453 03E 090753 rivet TA; 03/31/73 shipped date
N125674 Formula; Pic shows tag has rivets but can't read tag data
N1xxxxx 03E 130829 PHS: 4-6-73
N126875 104916 04A 150118 rivet
N128051 110641 04A 210089 rivet
N128590 111735 04A 230417 rivet Formula; 04/23/73 shipped date
N128702 111702 04A 230877 rivet Formula; 04/23/73 shipped date
N1xxxxx 115330 04C 280249 rivet TA show car
N129089 108073 04C 250541 rivet
N129498 104833 04C 270381 rivet ***
N129635 04C rivet Esprit
N129906 04C 290173 rivet Formula; 04/27/73 shipped date
N130104 114032 04C 300025 rivet TA; 04/27/73 shipped date; ***
N130124 113951 04C 360161 rivet ***
N130358- - - ? Formula; No Tag; 5-02-73 shipped date ID# 700428
N1xxxxx 115330 04C 280249 rivetTA show car
N130873 123502 04C 330137 rivet *** no phs; rivets looks aftermarket
N131165 121342 04C 340673 screw TA; 5-04-73 shipped date ID# 707421
N131359 121378 04C 350621 Rivet TA HFR; Ship date 05-10-73
N131959- - - screw Formula 5-10-73 shipped date ID# 722213
N132024 126040 04C 330781 screw? ***** 5-11-73 shipped date
N13240X 04C screw? ****
N13259912743604C410473 (hard to read) screwHFR; Formula, ship date 05-16-73
N132748 127245 04C 420193 screw
N132826 130206 04C 420473 screw *
N133537 131939 05C 450745 screw TA; 5-21-1973 shipped date ID# 749308
N1xxxxx13217805C470625screw TA
N1xxxxx 133677 05C 470489 screw
N134492 139325 05D 500346 screw
N134585 136196 05D 500665 screw
N134846 137732 05D 516733 screw
N135467 screw
N1xxxxx 139373 05D 530065 screw Formula
N136165 150094 05D 578794 screw??
N135254 154000 05D 560053 screw TA
N137131 156381 06A 610877 screw
N137168 163941 06A 620089 screw Formula; 06/15/73 shipped date
N137599 164238 06A 630813 screw TA; 06/19/73 shipped date
N137725 166045 06A 640323 screw SD TA; 06/19/73 shipped date
N1xxxxx 166231 06A 630233 screw Formula
N1379xx 06B screw
N138196 16341x 06B 660385 screw SD TA BVZ
N138433 163415 06B 670513 screw SD TA; 06/26/73 shipped date
N138639 183363 06B 680017 screw SD TA; 06/28/73 shipped Date
N1xxxxx 167117 06B 680521 screw
N138995 163414 06B 700009 screw SD TA
N1xxxxx 170011 06B 700809 ? TA
N1xxxxx 73214 06B 755824 screw N and not NOR; should be a one at beginning of bdy#?
N139423 16?158 06C 710801 screw
N139695 185825 06C 730055 screw SD TA
N140166 189420 06C 740721 screw
N141197 188814 07A 790473 screw SD TA
N142276 189807 07B 840085 rivetwrong rivets?
N142906 189151 07B 860525 screw
N142392 187923 07B 840553 screw
N143123 186183 07B 870429 screw
N143240 189214 07C 899816 rivet *? 7-20-73 shipped date ID# 916401
N143320 189708 07C 880241 screw
N143407 190487 07C 880556 screw
N143467 190887 07C 880829 screw
N143809 185403 07C 900281 screwSD 455 Formula
N144026 190389 07C 910221 screwEsprit
N144216 197393 07C 910913 screw1st bdy#9 looks like 0?
N144632 186236 07C 930533 screw
N144657 186977 07C 930?4? screw
N1xxxxx 187865 07E 900213 screw
N144683 187897 07C 930737 screw
N144921 ?????? 07C 940761 screw
N144933 185384 07C 950193 screw
N145023 201176 07D 762824 screw
N145274 07D xxxx53 screwTA rough tag
N145319 180026 07D 796083 screw
N145673 185075 07B 820621 screw
N1xxxxx 197865 07E 960213 screw TA SD