Welcome aboard April!
Others can confirm but I think PE's were 10-bolts so if untouched it won't be that.
On the Keystone Warrior thing, there was a drag strip near Winnipeg Canada operating as Keystone Dragways later called Bison Dragway.
Long shot but it may be worth searching their photo archives etc also running the Vin by George at GM Canada Vintage services, see links below.
Keystone/Bison website...
http://www.mts.net/~red67/index.html
GM Canada Vintage services...
http://www.vintagevehicleservices.com/options.html
Best o' luck w/ everything!.
[img]<<GRAEMLIN_URL>>/beers.gif[/img]
~ Pete