Originally Posted by 01WS6/tamu

4L80 crank spacer and ls series 4L60E flywheel solves the transmission question. Don't let anyone tell you a LS series trans is heavier, everything behind the pump to the tailshaft is the same as the Ls the difference being the converter and pump and one additional hole in the bellhousing. The only heavier LS trans is the 4L65E

Harness wise the easiest route is to use an LS series 99-02 truck harness and then weed out the 1998 engine management stuff from your existing underhood harness and then marry the two using this existing underhood fuseblock fuses etc.

Your current fuel pump will do the job.

As far as engine mounts their are a couple of other LS powered 88-99 OBS chevy trucks here. There are different ways of doing it and the best bet is to locate the people who have done it and then pm them with questions or pictures or related posts.

Originally Posted by Steved334

Is there a thread or video on what you were talking about with the harness. I’m about todo the same swap. And I have a harness and comp from a 02 Tahoe. Also what mounts did u use. Or recommend for bolt in application. No modifying or very little. This will be my first swap as well