E-50 StandardPanzer

The E-50 Standardpanzer was intended as a standard medium tank, replacing the Panther and Tiger I and the conversions based on these tanks. The E-50 hull was to be longer than the Panther, in fact it was practically identical to the Königstiger (Tiger II) in overall dimensions except for the upper and lower glacis plate layout. Compared to these earlier designs however, the amount of drilling and machining involved in producing these Standardpanzer was reduced drastically, which would have made them quicker, easier and cheaper to produce, as would the proposed conical spring system, replacing their predecessors' torsion bar system which required a special steel alloy.

Other sources show that a variant of the narrow-mantlet 'Schmalturm' turret designed for the Panther Ausf. F would have been used, coupled with a variant of the 88 mm L/71 gun.

As indicated by its name, the weight of the E-50 would fall between 50 and 75 tonnes. The engine was an improved Maybach HL234 which had 900 hp. Maximum speed was supposed to be 60 km/h.
https://en.wikipedia.org/wiki/Entwicklung_series