About a year after buying the 72, we were tired of fighting some of its gremlins. The main problem was the 350. It was was extremely hard to start once it was at operating temp and would die in traffic if the idle was set too low. On top of the oil consumption we were lead to search for a new powerplant.
We had a sbc 350 in the barn from a 95 Z71 with fuel injection that we were really tempted to install, but we stumbled across a local guy who was an excellent mechanic that had a reputation for his LS swaps. You can see where this is going!
It didn't take many joy rides in his previous swapped builds to convince us. So over spring break we sent the truck to him and swapped the 350/350 turbo combo for a LM7 Iron Block 5.3 backed by a 700r4 from one of our parts cars. We dropped the truck off on a Sunday night with the trans in the bed and on Wednesday morning he handed us the keys.
The donor for this engine was a 2003 Chevy Avalanche in a scrapyard with about 100k on the odometer, a 2003 was selected so we could still have the drive by wire unit.
This is his aftermarket ECU set up. It has a diagnostic port and the Smog, evap, and torque management deleted.
The 350 was sold to a friend who raced dirt track cars. He built the engine for his next car and told us the cam lobes were pretty worn. He had us come look at it after the top end rebuild and it sounded wicked! I wish I had a video of that motor running also, but He blew it up about 3/4 of the way through the season.
This motor by far has been the best thing we have done to this truck. It's smooth idling and in power delivery. Through the same exact exhaust system it has a much more mellow idle, but an awesome raspy backbite when revving. If you couldn't hear the fuel pump you would never know it was an LS swap. The power difference was also amazing, this stock 5.3 had more power in every range than the old 350 could dream of. The mpg's have been 17-18 now in all around driving and since 2011 this engine hasn't given us a single problem.
The transmission was a different story. The First 700r4 from our camaro parts car was a little tired. It slipped under WOT, and the installer told us if it was his truck the trans would be blown up before the weekend. I was able to get another year and a half out of it before 3rd gear stopped pulling on the way to town one day. We got the trans rebuilt and re-installed and it still had slipped under WOT, as of now it is still in the truck but we are currently getting a 4l60e built to fix this problem. We also used a recommended builder from the mechanic who did the engine swap
At the time of the swap we installed an aluminum tank in the frame of the truck. The tank is 18 gallons and comes from SoKyClassics here in Bowling Green. Ill have some pics of his later on also.