Ah..I think this would be my answer.
A shift knob boot retainer/collar in M10X1.25 pitch
In Black:
Black Shift Knob Boot Retainer Adapter for Manual Gear Shifter Lever M10x1 25 | eBay
VMS Black Shift Knob Boot Retainer Adapter Manual Gear Shifter Lever 10x1 25mm | eBay
Or Chrome:
Satin 2010 GT500 Shift Knob Boot Retainer Adapter for Manual Shifter M10x1 25 | eBay
VMS Silver Shift Knob Boot Retainer Adapter Manual Gear Shifter Lever 10x1 25mm | eBay
A shift knob boot retainer/collar in M10X1.25 pitch
In Black:

Black Shift Knob Boot Retainer Adapter for Manual Gear Shifter Lever M10x1 25 | eBay
VMS Black Shift Knob Boot Retainer Adapter Manual Gear Shifter Lever 10x1 25mm | eBay
Or Chrome:
Satin 2010 GT500 Shift Knob Boot Retainer Adapter for Manual Shifter M10x1 25 | eBay
VMS Silver Shift Knob Boot Retainer Adapter Manual Gear Shifter Lever 10x1 25mm | eBay