I don't know either with the notion this kit wasn't around in the ANH era. I can't confirm for certain either way. The only thing I can think of was the B/W photos were taken quite a while after ANH, but before 'Empire'. The Karl part could have been added during this period & not being an 'original part. This would explain a few of the other missing parts that show up in these 'early' B/W photo's, such as one possibly from the 312b on the starboard side mandible wall.
IMO, the Falcon got pretty beat up in storage between ANH & Empire so new parts were added & somewhere during this period the B/W were taken.
Stu
My minicraft catalog from 1977 lists #728 Anzio Annie rail gun and #732 Thor (Morser) 60 cm rail mortar as being available .
The squadron mail order catalogue from spring 1976 (no. 10) lists only 728 Anzio Annie as being new from Haegawa. No mention is made of Thor.
From the above I would speculate that the Haseqawa Thor (Morser) was released sometime between summer 1976 to December 1977. Minicraft Models INC. was based out of Torreance, California and was importing some or all kits directly from Hasegawa.