Another difference can be seen on the handles, where it says FORGED IN U.S.A. , <U.S.A.> and MADE IN U.S.A. .
Thanks, Tom, but I'm punting on that. I'm having enough trouble figuring out their model number/marketing scheme in the same production year, where all other markings
except the branding (Motor Spec vs < DC >) is identical, let alone taking on those kinds of differences, which are probably production era related.
I’ve always thought that the DC line was a response to Crescent’s less expensive Cee Tee line but I’ve never checked into it any further.
I think your intuition, which confirms mine, is good.
The 1946 catalog supplement had no price scheme and seems to indicate the Motor Spec and < DC > pliers are both made from tool steel, with the Diamalloy brand getting the alloy steel, which differs from what they were doing in 1951. But they gave the Motor Spec the same finish as the Diamalloy (double nickel), whereas the < DC > was just plated.
Just so we don't have to toggle back and forth between pg 5 and 6, here is the 1951 cat excerpt again.
By 1969 they had dropped the Motor Spec branding, but note that they were still essentially making a three-tier model line with a three-tier model numbering scheme. The "special steel" with "Polished nickel chrome plating" = K1x series, the "special steel" with "satin nickel chrome plating" = K2x series, and "high grade tool steel" with "Nickel chrome plating with satin finish" = K3x series.
The 1969 catalog included a PL and the pricing scheme indicates that K1x was top of the line, K2x was mid, and K3x was clearly economy.
It's a little risky to apply that retroactively, but it would be kind of confusing for their customer base to suddenly invert the whole scheme after they had been using it for a couple decades.