OK, Here's what I have to offer...I believe the typo is the model designation not the year based on the engine serial.
1929 engine serial numbers start with 1 and end at 1265800 (1265801 to 1365365 were not used on Chevrolet production).
1930 engine serial numbers start with 1365366 and end at 2100284.
Your engine Serial Number "17423" is low enough to believe it could have gone in a truck assembled in early April of 1929.
Additional fodder...Mid year 1930 the 131"wb "LR" (identical to the 1929 "LQ") was discontinued and the improved model "LS" 157"wb became the only 1-1/2 ton offering (it was also the first Chevrolet truck offered as a Dually).
Mike B
