what is the difference between the 2 starters? they have a different part number and I need to get a starter, unless a 5.7ls1 starter will work.

 

no clue...

do they look different, have you put them side by side?

 

The 6.0 with a 4L80 may have a different starter than a 6.0 with a 4L60e because the flexplate sets in further.I used my 5.3 starter on my 6.0,check a 6.0 part number from a SS or VHO or Denali.

 

AFAIK, they are all the same.
there is a short and a long bolt version tho.
worst case.... you would have to go to the dealer and buy one short bolt or one long bolt.
good luck.
i have a 2004 vette starter on my 2004 6.0 and its cranking fine.