I seem to recall that a change in ownership played a big roll in Wrangler no longer being the primary sponsor of the RCR #3. In 1986, VF Corporation, owner of Levi's bought Blue Bell Inc, the company behind Wrangler. I believe I remember reading articles in Winston Cup Scene that indicated that when Wrangler's deal when RCR came up for renewal, VF was unwilling to continue primary sponsorship, at least at the levels the soon to be three time Cup champion was commanding. How much GM's willingness to write a big check to their newest superstar, I can't say. If anybody has any more information on this, please come forward, but I'm under the impression that VF bailed, and GM was only too happy to step in.
Exactly, sponsors come and go. Lowes moved on. A new sponsor has took their place on the #48. So as far as I can tell, all is well under that roof.