B vs RB

68 thru 73? HP 383s were all RB due to the 3. 375 stroke. That's way I understand it. If it's got 3.375 stroke in 383 it was RB?
The RB's stroke was 3.75"
And:
383
220px-1959_Chrysler_B-series_383ci_V8_engine_in_a_Windsor.jpg
RB 383 "Golden Lion" engine in a 1959 Windsor
Not to be confused with the 383 B engine, the 383 RB had a 4 1⁄32-inch (102.4 mm) bore (with the long stroke of 3.75) for a displacement of 382.9 cubic inches (6,275 cc). It was only available in 1959 and 1960 on the US-built Chrysler Windsors and Saratogas; one of Trenton Engine's lines had been converted to the new RB engine (to make the 413), and demand for the 383 B engine was too high for the remaining line. The solution was to create a 383 RB to fill the gap until the plant figured out how to quickly switch from one block to the other.