i bought a flexplate at carquest for my 02 t/a,to do a m6 to th400 swap,anyways the flexplate has a weight on it.i thought the ls1's where internally balanced .thanks for your help.

 

jw in florida makes a crank adapter and that is all you need

 

https://ls1tech.com/forums/automatic-transmission/639693-ls1-style-engines-old-style-trans-th350-400-2004r-700r4-4l60e.html

 

still didnt answer my ? about the weight...

 

there is no weights on any of the 4.8,5.3,ls1,6.0's flex plates

they probly sold you a gen1 or gen2 flexplate you need a gen3 small block flexplate

 

i checked the fly wheel bolt pattern it fits an ls1..

 

i dont remember any weights being on my new or old flexplates...

 

doesnt matter if it bolts to your crank,, it isnt the correct flexplate, i have never seen a 4.8,5.3,ls1,6.0 with a weight on the flexplate

which flexplate you trying to run, the gen3 flat or curved, what crankshaft spacer/adapter are you going(gm or hughes) to use to keep the th400 converter

read my previous link, it is all in there