Only the DN's will do the 2.5 Khz steps necessary to program in one of the newer splinter channels, ie. 153.777500. The AN-CN models will do the new 12.5 Khz channel spacing spec, but only for non-splinter frequencies like 155.235000.
In many cases, earlier models will still be very serviceable for many years to come. But when an agency licenses and implements a splinter channel some time in the future, the earlier models won't be programmable to the new frequencies.
Please DO NOT email or PM me with general technical questions.
They should be posted on the forum. Let everyone have the chance to respond and to see each others' answers.