See this post on German MTB forum mtb-news.de: Diamondback Logos over the years
Bikes from 1986-1988 feature the rear u-brake under the chainstay like many MTBs of this era.
Exceptions are the following lower end models:
In 1989, it was removed from most models, but remained on the Fleetstreak and added to the Curaca
WIP
Rack braze-ons are usually found on older midrange bikes, since race bikes don't "need" them and they are not present for cost-cutting on low-end/newer bikes
1986 - Apex, Fleet Streak/APB
1987 - Arrival, Apex, and Ascent (top end of the range, before the Axis race bikes became a thing in 1988)
1988 - Arrival, Apex, and Ascent (not Ascent EX)
1989 - Arrival, Apex
1990 - Apex