I need a lower bushing (part # C21921) for a 1968 Series 1.5 coupe. Both SNG Barratt and XK Unlimited have the part but they are too large. Each has a metal outer collar which prevents the bushing from sliding into the selector lever (part # C20067). I have been told that the bushing should not have the outer metal ring. Does anyone know where I could get the proper bushing?