Page 182 - Makino,Tsutusi.DictionaryOfIntermediateJGrammar

(We will probably continue this joint research next year.)
-- %L%dL%4? Z o>%RR%B%bf & tf.5 5
$
[Related ~x~ression]
Another auxiliaq daro can replace karo without any change of meaning, as
in [I]. Note that the connections for the two auxiliaries are different: the
ones for dar6 are {V I Adj(i)inf] dar6 and {Adj(na)stem l N] {@ I datta]
dar6, whereas the ones for kar6 is Adj(i)stem kar6. (See Formation.)

Also to be noted is the fact that kar6 cannot be connected with the past tense,
but dar6 can, as shown in [2].
f:w8w I ir $A%
r
I,
5
[2] a. 'i 3 2 k:di B *%GltRPiki%;5.3 7': I(E)3 i / *%~3
(For John the stay in Japan was probably intriguing.)
li~d~b~?i
b. ;~t%f&to%~&d.~ 5 / *@?I 5 I,
7':
(The winter in Hokkaido was probably cold.)
The most basic difference between dar6 and kar6 is that dar6 can be used in
both spoken and written Japanese, but kar6 can be used only in written
Japanese. (cr> daro (DBJG: 100-02))