[88Ironduke]

I have a done a 5.3 4L60E install into an 81" Firebird. Nuggets of lore...

Motor mounts did not match my application exactly, life sucked. Get complete stands/adapter plates for the block that match your vehicleapplication. Don't go cheap, buy the set. Depending on far forward or aft the motor sets could influence your choice of oil pan. Match up the mounts so that the oil pan will clear. Went with DBW, looking back would rather deal with a cable. Add in the adjustable gas pedal assembly from the donor and there will be fabrication required in the floor. Keep the DBW pedal assembly far away from a welder... Don't ask. The conversion to a cable system will require a throttle body and very possibly a new ECM to play nicely with the new set up.

Wire harness was easy part, LS1tech.com, NastyZ28, and a few others have a really nice break out for the required goodies, optional goodies, and stuff to get rid of list. ECM will actually "lay" in a semi-stock location if you leave the required wiring alone. Mount to the drivers side wheel well vicinity and everything else lines up. Two or three relays and you can set up a running motor quick. The motor harness is actually pretty basic. Went with old school analog gauges and sending units. Only headache was oil pressure sending unit. Block has metric threads but Autometer set was standard thread. Adapter installed and good to go. Electric fuel pump will be required, advise in tank pump capable of 60 PSI with return. It was easy and return style system was effective.

I went ahead and installed a 4L60E tail shaft adapter to give both ECM reference input and a cable drive for the mechanical speedo. Cant say for sure how good buzz boxes or convertors are or their longevity but this was a permanent fix. Expensive... but bullet proof. Add in a custom cross member (refer to screwed up motor mount selection) and custom drive shaft (again, mounts)... You get the picture.

Ask about power steering pump if the donor truck had hydro-power assist versus vacuum power assist brakes. If the former is on the motor, it complicates the install but not bad

End result, frigging awesome power plant, fires up first crank when bone cold and runs great. Go for it. Burns tires no problem, sounds awesome and looks bad@$$ under the hood.

88Ironduke