This is what I found
1967 Plymouth GTX Production Numbers
Vin Year/Model Body Style Remarks Amount
RS23-7- 1967 Belvedere GTX 2 Door Hard Top 12,010 Total
RS27-7- 1967 Belvedere GTX Convertible 680 Total
RS2--7- 1967 Belvedere GTX All Models 12,010 Shipped
RS2-J7- 1967 Belvedere GTX All Models 426 HEMI 733 Shipped
RS2-J7- 1967 Belvedere GTX All Models 4-Speed 312 Shipped
RS2-J7- 1967 Belvedere GTX All Models Automatic 408 Shipped
RS2-L7- 1967 Belvedere GTX All Models 440-4 11,277 Shipped
RS2-L7- 1967 Belvedere GTX All Models 4-Speed 2,486 Shipped
RS2-L7- 1967 Belvedere GTX All Models Automatic 8,791 Shipped
Total = Total Production U.S.A., Canada, and Export Orders
http://www.plymouthgtx.net/information/1967-gtx-production.shtml