Have you downloaded a Vehicle Information Kit for your 1961 truck? Lots of great data.. here's a link: http://gmheritagecenter.com/docs/gm...hevrolet-Trucks/1961-Chevrolet-Truck.pdf

On the 63-66 trucks "Trim" = the applicable RPO code. Not sure about a '61. Go to page 36 in the pdf I linked above, page "Cabs and Bodies 3". Lots of pertinent data there and on the following pages.

Hope that helps!

PS: Want to part with that '65 'vette of yours? Got any photos of your rides we could check out?

John