G Atsma

Hard to say. The Gen IV rods were a running change. If your 2004 rods have the slip fit pin, you can use them. If press fit, no.

Country1982...

the reason I'm asking is when I pulled this Gen 4 apart it had spun 3 bearings those rods look pretty scored and the bearing doesn't fit them anymore I have a 2004 5.3 in the floor and it would save me 600 in a build I'm doing as charity for one of my employees who can't afford it

Country1982...

and by slip fit do you mean retaining clips because that's what the 08 has but no casting # on them

G Atsma

Yes, slip-fit will use the clips. Press fit will not use them

Country1982...

are you positive that is the only difference I don't want to dissamble a 120k mile running engine and they not work

G Atsma

The 04 engine will have 8cc dished pistons which were needed to work with the 61cc chambers in the 706 heads used on Gen III engines.
Gen IV engines came with 243/799 heads which have 65cc chambers, negating the need for dished pistons and giving it a little more compression.
The rods themselves should interchange as long as they are slip fit pins. The length is the same, along with all other dimensions.