From Uboat.net on the VII/42 :
The VIIC/42 was designed 1942-1943 and was intended to replace the then retreating VIIC, she had a much stronger pressure hull (with plating thickness up to 28mm) and a bit better offensive punch (16 torpedoes against VIIC's 14). Her diving depth was designed to be 200 meters with 400 meters as crushing depth (VIIC figures: 100/200 meters). These boats would have been very similar in external appearance to the VIIC/41 but with two periscopes in the tower as type IX.
All contracts for the VIIC/42 U-boats were cancelled on 30 September 1943 in favour of the new Elektro Boat XXI.
https://www.uboat.net/types/viic-42.htm
Good hunting,
FUBAR295