This is a great thread--- thanks to ALL you guys!!! Was considering 4L80E swap sometime ago but instead went with the Gear Vendors install to my 1008, finally, and it's a wee-bit disappointing that with the TH400/GVunit, you really only gain about 8-10 mph speed increase in overdrive. So now instead of screaming along with high RPM's to do 50-55 mph, I now can cruise an easy at 60-65 turning 2350-2500rpm, not bad for the slow truck lanes, but still not fast enough and more RPM's than I want to maintain engine's longevity.
Am currently driving the truck daily, 100 mile round trips.
This result makes now me ready for next logical step--- 4L80E swap, which will boost my final output to something like 2:62 to 1, as per GV's trans/gearing chart. So my next step is finding the trans locally, then a reputable builder, and with this and a few other good write-ups, plus the obligatory 2-3K OR MORE in $$$, BINGO--- I'll finally have a low-geared off-road capable, highway cruising, fuel pinching truck to expedition with... BTW; the GV unit helped truck gain in fuel milage with a combined city/highway of 17MPG, using GPS for accuracy. Looking forward to better!
P.S. Anyone's thoughts on an NA 6.2L/NV5400 swap instead?
Ciao~!