Shade tree ??? Sorry my friend but i've been in the auto business over 35 years. Not a back yard machinic. If you really beleive that motors from the 50's and 60's lasted as long as the new motors and being as trouble free then it shows who is under that shady tree. In the 70's garages did motor swaps weely. Ask your local garage how many motor swaps they do now. Ask your local yard how many motors they sold in the 70's every week and how many they sell now. Late model motors run 150 to 200,000 miles with no major repairs when maintained. 50's and 60's motors never did. Yes there were a few exceptions but not as a rule. It's a very well known fact in the industry that the late model motors are designed and built better then ever and last longer then ever.