Dimms squared from pivot are A: 10" 6/10, 270mm, and B: 16"1/10, 410mm when axle is near the front of the slot. These are for early swing arms, 52K to 66XLH/69XLCH. Later Sportster ones have a bend in the tubes and are 1" longuer.
Some variants in the early ones: K/KH/XL/XLH, fitted with long chain guard, machined/threaded cast tab near front right.
On XLCH, that tab is not machined/threaded, the smaller guard is fixed to inside threaded boss that is part of rear casting. Still later, round hole tab welded on rear right leg tube for stop light switch anchorage.