in which the set 954 is no longer available so we know that TLG only produced
this set for the US market in 1978. This set and 852 had a very short production
life.
(one interesting fact is that the box art on 954 is slightly different that its
European counterpart 852 since a 4x2 yellow plate was replaced by a 4x4 yellow
under the tail rotor. Having checked many photos, it seems there exists only
one version of the European box: the early version with box that shows the 2x4
yellow plate)
The slope 45 2 x 1 with bottom tube was produced for the first time in 1981 or
1982 and I am sure it never existed in 1980 or earlier. The reason I don't
know if it was produced in 1981 or 1982 is because I did not find any new sets
produced in 1981 that came with this slope but
- have checked many copies of used or new sets produced in 1980 and they all
came with 3040a (without bottom tube)
- have checked many copies of used or new sets produced in 1982 and they all
came with 3040 (with bottom tube)
So the year 1981 is far from 1978 and I am sure the slope 3040 with bottom tube
did never come with 954-1.