Vacuum question

I have an 89 with a vacuum disconect front axle. I can get a deal on a regular D30 with a better gear ratio. Can I simply swap the complete diffs, or should I just do a gear change in the axle I have?

Swapping out the whole axle is a piece of cake, as long as the new axle is the same ratio. Has to be the same as the rear.

In 91 they did away with the disco so you'll be fine. No 92 & later has a disco from the factory, just plug off your vacuum lines. You can hook up the 4wd light by using a switch from a non disco 231 if you need it. I always know when I'm in 4wd without it BUT some people need the idiot light. You will feel some binding in the axles without your disco but like I said no 92 up came with it so that's normal.