i would keep what you have, unless you need a new truck. most of the things on there are totaly minor and not worth even mentioning and every brand will have thoes kind of issues. you had the short block replaced befor so it was relitivly new i am assuming. unless it is making weird noises and not running smooth I wouldnt even worry about the antifreese being injested. all warenty will only pay for what is determined to be broken, so they fix the problem, reassemble, and test. if somthing is still wrong they fix that problem. if your truck made it out there isnt a problem left. also is it still under warenty? if it is pay the extra little bit and extend it if you are worried to give your self a bit more piece of mind.
Steve