Audio system, AM/FM stereo with CD player, auxiliary jack, 2 USB ports and SD card reader

2015: Base, WT: S; LT, Z71: not offered; the upfitter lists name it infotainment system, base HMI; GM Authority's 2018 Colorado page says IOB replaced it on Base and WT for 2018

2014: 1LS, 1FL, 1SA: S; 2015: 1LS, 1FL, 2FL: S; printed with a letter O (no zero form in GM's lists)

1LS, 1FL, 2FL: S; the 2016 guide drops the CD player (TG5 is a separate option from 2016)

deleted for 2018 (GM's 2018 Impala RPO change list, GM Authority), which places it in 2017

2017: GM's 2017 Silverado 2500HD order guide

the code is written with the letter O in GM's lists.

LS: S; LT, LTZ: not available; the 2016 guide gives the LS IO5 instead; the code is written with the letter O in GM's guide and lists; the Silverado K2XX doc reads it as the 4.2 inch color display radio

2015: LS: S; LT, LTZ: not available; 2016: Police Vehicle and Special Service only (Special Service: S), with one USB port, the 2016 retail guide giving the LS IO5 instead; the code is written with the letter O in GM's guides and lists; the Silverado K2XX doc reads it as the 4.2 inch color display radio