spd500

iTrader: (1)

My motor has castings on the back that say 4.8/5.3 . How do you know for sure which one it is ? I was told it was a 5.3 by the junk yard it came from , but want to make sure I got the right thing .

NemeSS

iTrader: (127)

Usually if still visible it will have a paint mark or dab from GM on the displacement. Sometimes just a dot or a check mark
Usually in rear of block or front of block. But if has accessory bracket and or flexplate it's hard to tell just by the exterior.

Blk98Vert

iTrader: (2)

5.3s have dished pistons, 4.8s are flat

dodson55

iTrader: (18)

if its a 99-early 07 pull a plug and take a good flashlight and look inside at the pistons if they are flat top its a 4.8 if they are dish it a 5.3 you can also feel for it with a skinny screwdriver if you know wjat you are looking for

hemiqc2003

Look for the paint mark through the 4.8/5.3 on the back of the block. That is the easiest way to tell.

spd500

iTrader: (1)

There is no paint mark on the back of the block , just the casting that says 4.8/5.3 . I tried looking in on of the spark plug holes , but can't see anything . Is there a way to look up the numbers , or any other way to tell ? Is the fuel injection system the same system , of can I maybe tell what it is by the fuel injection system ? Thanks for your input .

6898camaross

It should have a little tab on the head gasket sticking out that says 5.3/4.8

dodson55

iTrader: (18)

the only way to tell is by the pistons rods and crank every other piece is the exact same on the engines if you are going to change oil pans look at the crank part number other then that the top of the piston or length or the rod is the only way to tell if u pull the piston to almost tdc you can see if it is flat or dish pistons thats the way i have always did it

spd500

iTrader: (1)

I tried looking for the little tabs , mine are blank . I think this may be a rebuilt motor , it is really clean , and the oil looks like new oil on the dipstick .

I will give that another shot , I pulled a plug earlier but didn't think to bring the piston up to TDC

OK , with the piston at TDC you can see

The pistons are dished , so I guess I got the right motor

Thanks for the help guys , just wanted to make sure it was the right motor before I got too carried away with spending money on everything to get it to fit in the boat .

sandeggo

the only way we could tell on my 07 motor was to call a local dealer and they looked up the number that is on the driverside rear part of the block right behind the head. the head gasket tab said 5.7 and the block said 4.8, 5.3 with dished pistons.