I don't think there was an exact date. Sometime in the past several years is about as definite as you are going to get on this one. As much as many of my Randall collecting friends toil to date things...some things cannot be dated that closely. I could probably go back over old invoices and find orders dating one way or the other. A couple of printings back the Randall catalog started including an insert photo of the #10-3", "DP". Let's say about 2002-2004. I have orderd #10-3" since then and not requested the "straight" blade (point) and received them. Things like this make it difficult to "exact" such subtle changes.
Gotta tell ya'...A couple of really good ordering questions today! I hope the answers are nearly as good.
Best, Capt. Chris