Here are a couple of threads with a variety of opinions about how to dispose of old gas. If it were me I'd check with my local hazardous waste recycler. Perhaps they have empty containers you could use, since you have so much needing disposal.
http://www.diyforums.net/old-gasoline-disposal-385808.htmlhttp://www.eng-tips.com/viewthread.cfm?qid=179536&page=2And confirming - yes the early hydramatics had no park position. The shift pattern for many years was N Dr Lo R. The pattern was problematic, but GM left it in service for many years due to retooling cost. With a heavily laden vehicle, it was natural to downshift to low when descending a grade. When the vehicle didn't decelerate as expected (because of the heavy weight), the driver would downshift into low a second time, inadvertently shifting into reverse - occasionally causing complete loss of vehicle control. I experienced this twice as a child which scared the crap out of everyone in the car, but did not result in a crash.
Just something to consider when evaluating the cost to restore something to stock, that might better be upgraded to something more modern.
