Here are the codes for the 250. You can look on the door for the tag that has specs, on of which is the axle. That code should be one of these, to tell you what you had.
27 – 3.31 Non-LS
26 – 3.73 Non-LS
Maybe someone can decipher the number from that rear end tag, but I can not. What you can do is jack it up and see how many times the drive shaft rotates in relation to one wheel turn. Less that 3 1/2 would be 3.31, more than 3 1/2 would be 3.73.