Huge help!!!

Ok i need some help here i was wondering what i need to do. to get 22 inch rims on my body droped sonoma in the rear. the rims that i am thinking about are a 9.5 width and i was planing on going with either a 295/25/22 tire or a 285/30/22 tire. here is where my problem lies. i have see 22's on the rear b4 and i heard taht the rear end needs to be shortened. is this true? i also heard that you can use the rear end from a blazer as it is shorter is that true? also what backspacing would i need and offset?