Actually using the TH350 transmission with the 4L80 crank spaces the converter just right. Thats the setup Im using in my bonneville. I used the 6.0 flywheel and it worked great. You wont need a hub spacer.

 

so, let me get this right. the 99 6.0 will bolt right up to the th350 using the oem flexplate, no pilot adapter/spacer is needed. we have a set of ls1 heads here, they wouldn't be any improvement over the cast iron headswould they?

 

Only improvement would be weight savings really. cause the 6.0 heads do flow better.

 

This is true as I ran into the same issue with my 99 6.0 engine for my swap, but I bought it anyway and decided to go the 408 route despite the extra dough. The 6.0 heads are the way to go in my book as they are cast iron replicas of the LS6 head, only with larger CC's. If I wasn't running spray I would mill them down for more compression.

How's the carb setup perform on these motors?

 

so i went to see my buddy today. he said it is an 01 motor, but he might just keep it and throw in a vehicle a spray the hell out of it for fun. so i may end up with the 5.3 motor. any tips on these.

 

get it and bore it to 3.900 bore and get some stock 5.7 pistons & rods.

 

the carb set up is sweet and its simple. Everything plugs in and you hook up a power, ground and ignition on the MSD and its ready to go. Im fixing to pull mine out of my bonneville and stick it in my 96 tahoe (leavin it carbed and puttin a 200-250 shot on it)