Thanks kindly for the reference which I successfully dug out. My copy of Doug's great work, autographed! Don't recall where or when. And definite point to you chubman! Likely should be 'point set'.
But just my personal experience, the guns I've owned and the several I now own... All counter. I used to ping on those white spacers - lack of - as distinguishing such as the Model 36 from the vast majority of Model 336 at ten paces in racks. That as it took some time to accumulate my several postwar specimens:
Model 36 carbine, sporting carbine & rifle & then to improve my specimensl originality & condition. It was in those days, 'pre Murray'
that I developed that habit and observation!
I suppose, the possibility of a sudden "white spacer craze" & retrofitting. But, doubt it! Based on his 'authority' which I do respect even in memorium, to yield. In my illustration above with butt plate, that's a "G" serial number rifle. I've also got two "H" RCs, both displaying "white".
Go figure!
Best & Stay Safe!
John