Ok stupid question-plug wires

Ok, so here it goes. I went to Autozone for some new plug wires. I tell the guy I have a 90' Cherokee 4.0L and I get the bosch 09280 plug wires. I go home. I take them out of the box and they are all the same length. I tried to get them on but 2 of them are too short.

So I drive back to autozone and tell them I have the wrong ones, he says no but we will check another box same thing. I said try a 91 and low and behold I get the right ones 09281. Now for the questions?

Did bosch AZ screw up?
Does anybody else have this problem?
Do I have a 91 engine and how do I tell?

Bosch screwed up.

The distributor is in the same place. There should be two long wires, two short wires, and two in between. You're lucky the other set fit, because the coil wire for the HOs is shorter than for the non-HOs.