includes a generally cylindrical ratchet insert 30 the main body of which is dimensioned to fit in the counterbore 26a of the housing body 22 the insert 30 having a reduced section 31 substantially square in transverse cross section and a further reduced cylindrical end 32 respectively dimensioned to fit in the square portion 26 and the bore 25 of the housing body 22 the insert 30 has an axial bore 33 therethrough with an internally threaded portion 34 adjacent to the rear end thereof and a counterbore 35 at the forward end thereof the insert 30 has a front end face 37 and is dimensioned so that when fully seated in the housing body 22 the end face 37 is substantially coplanar with the front end surface of the housing body 22 as can best be seen in fig3 formed in the front face 37 are pawl cutouts or recesses 38 a pair of bores 39 are formed in the insert 30 extending outwardly toward the periphery of the insert 30 from the pawl cutouts 38 one shown in fig5 referring in particular to fig3 and 6 the ratchet mechanism 21 includes a ratchet gear 40 which is rotatably received in the counterbore 35 of the insert 30 and has a reduced end 41 received.