D3060120A is the full NA file [including MX]. The D1279200A is US & CA only. Otherwise they have the same views afaik. Depending on the original LM maps subscription or OEM map update [All NA, Lower 49 US, US & CA, CA only or MX only] Garmin will supply the corresponding regional JCV file too. My US 765 has 4GB as would yours. However in the case of the limited memory 2GB 1xxx series they supply a cut-down smaller file with quite limited views. The larger JCV files can be put on a microSD [Garmin/JCV/*.jcv] in place of the cut-down file. 1xxx were not given full NA as OEM i think. My US 1300 had lower 49 only and my US 1490 had US & CA.