Colchester Mastiff 1400 / Clausing 21" New Tailstock imperial screw and nut 

Imperial screw number 42449

7/8 Diameter x 5 TPI x 9"1/2 including undercut, left hand

Collar 1.463" x 3/8

Handwheel shaft section 1" x 3"11/16, woodruff 5/16 key

Small thread 5/8 BSW x 15/16

Imperial bronze nut number 42405

Machined diameter 1"3/8 x 1"1/8 long 

The last photo shows the screw before the protective plastic was removed 

If you require any more information please email me

Other Harrison and Colchester parts available