Official NBS V6 to GENIII V8 swap Guide
#304
#307
I did a swap on my 2003 Silverado. Did everything mentioned on this post. But my rpms are crazy. 3k on 60mph. Left the v6 tranny with the 5.3 flex plate. Was reading something about a spacer needed. Any help ?
#308
100% Redneck
No spacer needed. You may have a shifter cable issue but it sounds like the trans cant find 4th gear. Count the shifts to make sure you're in overdrive. The V8 crankshaft will turn the same RPM's as the V6 if the rear gear ratio is the same. Make sure the tow/haul button on the shifter is not activated either.
Last edited by RedXray; 05-18-2019 at 12:10 AM.