The ornamental design for a universal tanklever, as shown and described.
FIG. 1 is a top front perspective view;
FIG. 2 is a top plan view;
FIG. 3 is a front elevation view;
FIG. 4 is a bottom plan view;
FIG. 5 is a left end view;
FIG. 6 is a right end view; and,
FIG. 7 is a rear elevation view.
The broken line showing portions of the lever is included for the purpose of illustrating a portion of the lever that forms no part of the claimed design.