Tanks Used?

The German tanks were actually M-41 Walker Bulldog light tanks, which had just entered service in 1955. At the end of WWII, all German tanks not relegated to museums or appropriated for use by the winning side were scrapped in accordance with the surrender treaties.

The American tanks were M-4 Shermans which at that point were nearing the end of their service life. The Sherman was the backbone of the US Army armored force in WWII, but in real life, with the event for which Murphy was awarded the Medal of Honor, the burning vehicle he was standing on was an M-10 tank destroyer, which was no longer in service but had the same chassis as the Sherman, so that the untrained viewer would probably be unable to tell the difference between the two vehicle types.

MadTom pretty much answers the question.

The only thing I want to add is the American side tanks used in the movie, the M4's, were of the Korean War type. This can be seen by the shape of the rear of the tank. The models used in WWII had an inverted U backplate while the Korean War models had a fold down horizontal plate, like for water skiers.

Probably only type that was available on Ft. Lewis in 1955.