the LJ78 and the HD 77 series all share the same body, the trim level is different. the PZ comes with the R151, the HZ comes with the H55F and the LJ comes with the R151. none of the 77 series up to 94 came with the H150 H151 trannies. we can not get newer than that so i can not answer your question properly.
the truck is on the road, the paint is not completed due to no heat in the garage, then when i finally got the heat working again the next day the garage was gutted and the cement got busted up. a pit is now dug and the bottom floor finished. Monday the rest of the floor will be proured then insulation is sprayed in. it will be a few weeks before i can get it painted.
i did to a gentle 0-100 km run. 12.4 seconds but this isn't accurate since i was running 32" tires and the speedo is set for the stock 29".
now you compare (just for the fun of it) with a stock LJ78 with the 2LTE and that run is 28.7 seconds. even if you have a LJ78 rrunning better than most it is 21 seconds. once i get everything tweaked i will give it another test run but i can say it is much nicer to drive now.
since it is just a 4 speed top speed is limited to 130 k/h but that is enough to cost you $10,000 and a crushed vehicle in Ontario in this area. it is real hard to keep it at 90 k/h, it creeps up to 110 very easy.
would i recommend a swap like this?
to replace the head on a 2LTE costs $4000
to upgrade the rad is $500
to upgrade the exhaust is $700
to do the other mickey mouse stuff is another $600
the cost to do this install is roughly double that total but you end up with better drivabliliy, reliability, better starting, more power and fuel economy will be better as well. there is no loss to the swap.
you end up with coil suspension, 4/90 gears, comfort.
i would recommend going with the R151 for a DD instead of the R141. that OD is really needed. i will be running the 35s once i get it painted to drop the rpms.
i do have some more pics to post up but no time at the present.
cheers and thanks for following along.
<BTW, if i add the propane to this truck the performance will drop another couple / 3 seconds. that is the duramax run time.>