Straight axle on a 89

Here's the deal... I plan on liftin my 89 Bronco as well as doin a few other things. I would like to clear 38s and my boyfriend was tellin me that it would be best if i put a straight axle on it. i kno that it will probably be in my best interest so that i wont have allignment problems and such. We have found one in good condition for $125 and i wanted a second opinion.:screwy: