  Non-compact G_2 holonomy metrics that arise from a T^2 bundle over a
hyper-Kahler space are discussed. These are one parameter deformations of the
metrics studied by Gibbons, Lu, Pope and Stelle in hep-th/0108191.
Seven-dimensional spaces with G_2 holonomy fibered over the Taub-Nut and the
Eguchi-Hanson gravitational instantons are found, together with other examples.
By considering the Apostolov-Salamon theorem math.DG/0303197, we construct a
new example that, still being a T^2 bundle over hyper-Kahler, represents a non
trivial two parameter deformation of the metrics studied in hep-th/0108191. We
then review the Spin(7) metrics arising from a T^3 bundle over a hyper-Kahler
and we find two parameter deformation of such spaces as well. We show that if
the hyper-Kahler base satisfies certain properties, a non trivial three
parameter deformations is also possible. The relation between these spaces with
the half-flat structures and almost G_2 holonomy spaces is briefly discussed.
