A mounting frame (40) for attaching a backhoe (42) or other implement to a lift arm (24) of a vehicle, such as a compact loader (10), includes an upright arm (50) on the mounting frame (40) that is positioned ahead of and adjacent to a forward portion (26) of a lift arm (24) of the loader. The upright arm (50) carries a pivoting locking handle (54) at a first pivot (66) and a locking link (52) is pivotally supported on the locking handle (54) on a first pivot pin (58). The locking link (52) has a second pivot pin (59) that can be moved to be supported in an existing pin sleeve or bushing (38) on the lift arm (24). The pivot pins (58, 59) on the locking link (52) are positioned so that when the locking handle (54) is moved to a locked position, the line between the axes of the pivot pins (58, 59) on the locking link (52) goes over center with respect to the pivot axis of the first pivot (66) of the locking handle, and a hook end (60) of the locking link latches onto a locking projection (66) on the upright arm (50). The mounting frame (40) is held in a fixed position relative to the lift arm (24).