Well after pulling the oil pan last night I found a lot metal shavings in the bottom of the pan (kind of copper colored on one side). Since i started this thread the tractor has sat in my driveway and leaked probably somewhere around 2 quarts of oil, this came from leaking seals around the drain plug bolts. I didn't get a lot of history on this tractor because I purchased it from an older lady who's husband had passed away and all she said was it had engine problems. But now knowing the tractor was leaking oil profusely I believe someone started this tractor after it had sat for a while and leaked most or all of the oil out of the engine and this caused a rod bearing to spin thus causing the knocking sound and validating my suspicion all along that this was probably the most likely cause for the engine problems she kinda described. The next course of action will be to check the crank and figure out if a total tear down splitting of the tractor is required.