Presented are tabulations of the power and power efficiency of four nonparametric tests (rank-sum, maximum deviation, median, and total number of runs) for the difference in means of two samples drawn from normal populations with equal variance. The cases considered are for equal sample sizes of three, four and five observations and alternatives $\delta = | \mu_1 - \mu_2 |/\sigma$.
W. J. Dixon. "Power Under Normality of Several Nonparametric Tests." Ann. Math. Statist. 25 (3) 610 - 614, September, 1954. https://doi.org/10.1214/aoms/1177728732