Is it unsafe or harmfull for a 2001 G.V. 4x4 with 2 tires of a different make and tread patern on the front as opposed to the back? (they are still the same size) I heard this was unsafe for the drivetrain

I don't think it will harm the drivetrain unless it's different in diameter, different makes have different final sizes for their tires, so make sure they're the same. More for in the winter it's nice to have the same tread pattern so the tires follow one another better, not so much the tread, but the overall mold shape of the tire.

it's hard on bearings ,espescally if there used tires, that are wore , it's like putting a regular tire on one side and one of those skinny donut spare tires on the other... yah catch what i'm sayin.... aslong as you run them both on the back or both on the front.. you should be good that way...

Thanks fellas, I measured the front tires and although they are all the same size, the front ones measure 1/4 inch larger in whidth than the rears. I just purchased the vehicle from the dealership for $13000 cnd. I believe I should go back and have them install 4 matching tires.              Thanks