Sorry for the bad answer, but nope. The older engine is not a Vortec and you can not swap out a fuel injected engine for a carburetor engine, unless you planing to use it as an off road vehicle only, and not to mention the transmission on the 98 4L60E is electronically controlled with the fuel injected engine combination. Keep me posted, be glad to answer any more questions you may have and help you get your truck running 100% again soon.