First of all, thank you for the add. I am freshening up my 49SP and my 52E. Both well maintained and well kept saws. My question is two fold..I know that the pistons for these saws are interchangeable but is there any advantage in putting a 52 piston in a 49 or vise versa. Second, should the wrist pin be a slip fit. I assume so but upon removal of pins in both saws the pins wear very snug (not slip fit) Any thoughts? Thanks in advance for your responses.