Quote:

and then I will want to upgrade what ever needs it to make it live for many many miles.



Maybe I have a good one, but I do keep the trans fluid clean. My '91 D150 A-518 has never been apart(nor the 360ci), going on 326,000 miles. Did a 1150 mile round trip to NC, empty car trailer down, loaded back. Those NC VA hills put my truck to the test! I'm not sure how long I'll let it go before I rebuild it.