I found an article by Don Bunn on the
chevytruck.org site that states "Major engineering changes for 1963 included replacing the light-duty model's torsion bar front suspension with coil springs and replacing the former standard six cylinder engine family with all new 230 cubic inch and 292 cubic inch sixes. The former 235.5 and 261 cubic inch sixes remained the standard engines for K10 and K20 pickups only. A restyled grille freshened up all pickup's front appearances."
So there, the 235 and 261 were carried over to 63 in K10 and K20 trucks. If this article is accurate.
