PST Adjustable UCA spacers

I just measured the spacers that came with my RMS uppers. They're installed so the measurements I took may not be perfect, but they'll be close enough for you to make some if you can't find any. They were 0.780" for the long ones and 0.370" for the shorties. The long ones go towards the front to gain a little caster.

Before you make them, I'd measure the width of your heim and the inside dimension of the mount. Maybe even just split that into thirds and make one spacer one-third, and the other two-thirds.