[68LSS1]

Yes, the 5.3 and 6.0 are included in the LS1 family. Ther are externally the same size and parts are interchangable to some degree. John at Speartech is great and his work is of the highest quality. I'm not sure how similar the car and truck set ups are as far as PCM and VATS (vehicle anti theft system), etc but I can tell you about a LS1 swap. You can do the harness yourself. You WILL need the Helms books for the year of vehicle it came out of for the pin outs of the PCM. For a LS1 swap you can delete the rear O2's, fuel level sensor, air pump/egr, oil level sensor etc. You will alsi have to wire in the diagnostic connector which John sells. But you then will have to send the PCM out to have these items deleted or it continually sets codes. Same thing with VATS (it will not start until VATS is removed). Or you buy LS1edit and do the programming yourself (which is around $550.00). The only other option is a stand alone set up like Accel DFI or FAST but they are around $3,000 for those. Again I'm not sure how much alike the 5.3 truck set up is but I'm sure it's similar. If yu can find out about the VATS in that year truck maybe there is a BCM you can pull and use to take care of that (probably need ignition switch also). Not worth the hassle and extra wiring if you can get rid of it.
I don't want to discourage you from this swap as the LS1 engines are great but don't forget you will need a whole new fuel system, a 300.00 box to convert the digital speed sensor signal to something your dash can use (or go aftermarket speedometer/tach) among other things. Good luck.