6. (10 points) On a new road that is $3000 \mathrm{~m}$ long, power poles are to be erected at equal distances along one side, starting from one end. According to the original design, the poles are to be spaced $50 \mathrm{~m}$ apart, and the pits have already been dug. If the spacing is changed to $60 \mathrm{~m}$, then $\qquad$ new pits need to be dug, and some of the originally dug pits will be abandoned.
【Analysis】According to the problem, first calculate the number of pits originally dug and the number of pits to be dug now, then find out how many pits overlap. Subtract the number of overlapping pits to be retained from the number of pits to be dug now to get the number of pits still to be dug. Subtract the number of overlapping pits to be retained from the number of originally dug pits to get the number of pits that will be abandoned; solve accordingly.

【Solution】Solution: The number of pits originally dug is: $3000 \div 50+1=61$ (pits),
The number of pits needed now is: $3000 \div 60+1=51$ (pits),
The least common multiple of 50 and 60 is 300, meaning pits should be retained every 300 meters, totaling: $3000 \div 300+1=11$ (pits),

The number of pits still to be dug is: $51-11=40$ (pits),
The number of originally dug pits that will be abandoned is: $61-11=50$ (pits),
Answer: 40 pits need to be dug again, and 50 of the originally dug pits will be abandoned.
Therefore, the answers are: 40, 50.