OEM open box never used MTD Remington trimmer Lower Shaft Boom Assembly 753-08544 for trimmer RM2510 with two-piece shaft. It is 32" long overall measured along the outer side of the curve.  It may fit the same trimmer model sold other brand names.   There is another style of the RM2510 trimmer that uses a one piece shaft that is about 45" long (My one piece Remmington RM2510 used shaft #753-05748)