How long until you do the 5 speed swap? If you are planning on doing it withen a year or so, just wait. Unless you just like swapping parts for the fun of swapping parts. The money you save (all that nickel and dime stuff) could get you the 5 speed a little sooner.<br><br>As for will the C4 last with 38s? Depends on a lot. How hard do you push it, how strong is your engine, gearing, what condition the tranny is in right now, blah, blah, blah....<br><br>As for swapping, it could be a good idea, you might decide that you like an automatic better for what you do. Then again, you might be happy with the 3 speed the way it is.<br><br>Basicly, yea you can do it. But only you know the condition of the parts and how you will treat them. It sounds like you want to try it, or you wouldn't have asked the question.<br><br>It's not much of an answer, but we know you will decide one way or another.