Hi everybody I have a question to do with the slant six engines, what years were the best years to get.?

I understand from a mechanic I deal with that 1977 and newer slant six motors are all made in Mexico and have much more quality control problems with them then the older engines, he said timing gear problems was one issue and valve problems is this true or not.?

1976 or older slant 6 at the wrecking yard is harder to find these days, I was also wondering
how good that engine would work out in a one ton dump truck that has a standard transmission
for hauling roof shingles to the dump, would it be ok for that, or would there be not enough
power there to handle that job.?

I had trouble one time, I had a 1973 slant six in a Dart and my engine eat the oil dipstick, I pulled it out one day and there was 2 inch chunk of the stick missing. \:\(