What to do with rad flush waste?

As tempting as it is to take a leisurely stroll to the sewer drain in my backyard, I can only assume it would be a bad thing... :nono:

Does Murray's or other parts stores take that stuff? What do you transport it in? About how much should I expect to have... 5 gallons, 10 gallons, a teaspoon?

Should the car be level when draining, or is it OK to jack up the front? or should you jack up the back to make everything drain out the front?

thanks for your help...

I don't know about auto parts stores taking back used coolant and such, but a lot of recycling centers and land fills will take used oil and coolant at almost any size (not like shop amounts but home do it yourself amounts).

Once you do the initial drain you should have about 1.5 to 2 gallons of used antifreeze. Most local landfills have a recycling are that will accept used hazardous waste, such as oil and glycol products. The best thing is to just put them into plastic containers, either what the replacement came in or gallon milk jugs, and take them in.
You DO NOT want to dump it in the backyard. Other than the hazards to animal life in the area, leaching of the product into the aquifer (water table) and other environmental hazards, there is also the problem of the EPA, State, Commonwealth or Provincial Environmental Agency or other governing body - or nosy neighbor - turning you in and making you pay fines.

I have heard of some parts stores taking old coolant, If you only have a gallon or two try your local auto shops, they may help you out too .

What about the position of the car? Does it need to be level, leaning forward, leaning back?

When you drain from the radiator it should be level. If you drain from the engine block plug, you can have it level or on a slight incline.
The safest way to work on your truck is with it level, so that is what I would suggest.
There are numerous threads about cooling system maintenance, and I believe one of them is in the FAQ section, so you might want to read through them.
Good luck.