It looks like this Part has been superseded by LEGO Part 3002 Brick 2 x 3.
There are two known mold versions of this part:
3002a Brick 2 x 3 without Cross Supports
This is the original version, introduced in 1958. The brick walls are slightly thicker, and the two tubes stand alone, without any connection to the side walls.
NOTE: all printed versions are 3002a.
3002 Brick 2 x 3
This is the modern version, introduced in 1979. The brick walls are slightly thinner, with two inside ridges on the short sides, and three inside ridges on the long sides. The two tubes are connected to the walls by cross supports.
The mold comparison image shows both versions. If unsure, use the modern version 3002.
Earlier alternate versions had no buttom tubes and were slotted (bslot03, bslot03b and bslot03c: 1953-1956), followed by a non-slotted/hollow bottom version (3002b: 1956-1958).
Basic Brick Quicklinks:
Click on a colored part below to see the Sets and MOCs that use part 3002a Brick 2 x 3 without Cross Supports in that color. You can find an overview of all LEGO Colors here.
If a color is missing, it probably needs to be added to a Set Inventory.
There are 2 Mold variations of part 3002a - Brick 2 x 3 without Cross Supports in the database, in use between 1954 to 1989. See Molds and other related Parts.