What lore exists for the Desert Rangers?

What lore exists from the original Wasteland with respect to the Desert Rangers? Here's what has been mentioned about them as found in the upcoming Wasteland 2 project:

And lastly I wanted to include a description of the Desert Rangers background, as many players are not familiar with them:

On the same day that the U.S. and Soviet Union were attempting to extinguish each other, a company of U.S. Army Engineers were in the southwestern deserts building transportation bridges over dry riverbeds. They worked deep in the inhospitable desert valleys, surrounded by a number of survivalist communities. Located directly south of their position on that day was a newly-constructed federal prison. In addition to housing the nation’s criminals condemned to death, the prison contained light industrial manufacturing facilities.

Shortly after the nuclear attack began, the Engineers, seeking shelter, took over the federal prison and expelled the prisoners into the desolate desert to complete their sentences. As the weeks passed, they invited the nearby survivalist communities to join them and to help them build a new society. Because of each community’s suspicions towards one another, times were difficult at first. But as time nurtured trust, this settlement -- which came to be known as Ranger Center -- grew to be one of the strongest outposts. Ranger Center even proved powerful enough to repel the hands of rancorous criminals who repeatedly attacked in attempts to reclaim what was once “rightfully theirs.”

The citizens of Ranger Center, after first believing that they were the only ones who survived the nuclear maelstrom, soon realized that communities beyond the desert’s grip had also survived, Because they had such success in constructing a new community, they felt compelled to help other survivors rebuild and live in peace.

Toward this end, the Desert Rangers, in the great tradition of the Texas and Arizona Rangers a century before, were born.

What (if anything) more exists for them from the original game?

The text you quote there was taken from the original manual for Wasteland. Here is the full text:

The following is an excerpt from The History of the Desert Rangers, The Early Years, by Karl Allard, 2087, Allard Press, Ranger Center Hardbound pp. 293,$20 gold.

Tensions grew with the coming of 1998. The United States' Citadel Starstation was slated to be fully operational by March, Soviet charges that the space station was merely a military launching platform alarmed a number of nonaligned nations. The right wing governments in the South and Central Americas, many of them set up by the U.S. during the Drug Wars (1987-1993), pledged their support to the U.S. The NATO nations, including the new African members also declared their alliance with the U.S. That move forced most of the remaining neutral powers to join the Soviet protest. In six short weeks, only Switzerland, Sweden, and Ireland continued to declare themselves neutral nations.

Two weeks before Citadel was due for full operation, the station transmitted a distress signal. Immediately after the message was sent, most of the satellites orbiting the planet were swept clean from the sky, leaving the great powers blind. In military panic, each sent 90 percent of their nuclear arsenals skyward. Although the destruction was tremendous, it was not complete. Pockets of civilization remained, some even oblivi- ous to the military exchange.

On the same day that the U.S. and Soviet Union were attempting to extinguish each other, a company of U.S. Army Engineers were in the southwestern deserts building transportation bridges over dry riverbeds. They worked deep in the inhospitable desert valleys, surrounded by a number of survivalist communities. Located directly south of their position on that day was a newly-constructed federal prison. In addition to housing the nation's criminals condemned to death, the prison contained light industrial manufacturing facilities.

Shortly after the nuclear attack began, the Engineers, seeking shelter, took over the federal prison and expelled the prisoners into the desolate desert to complete their sentences. As the weeks passed, they invited the nearby survivalist communities to join them and to help them build a new society. Because of each communities' suspicions towards one another, times were difficult at first. But as time nurtured trust, this settlement (which came to be known as Ranger Center) grew to be one of the strongest outposts. Ranger Center even proved powerful enough to repel the hands of rancorous criminals who repeatedly attached in attempts to reclaim what was once \rightfully theirs."

The citizens of Ranger Center, after first believing that they were the only ones who survived the nuclear malestrom, soon realized that communities beyond the desert's grip had also survived, Because they had such success in constructing a new community, they felt compelled to help other survivors rebuild and live in peace.

Toward this end, the Desert Rangers, in the great tradition of the Texas and Arizona Rangers a century before, were born.

There isn't much "official" lore beyond that. However, the Wasteland Survival Guide, which was a "cluebook" from the old days, is really well-written, and has some great "lore", though I don't know if it is considered "canon" or not.