well i was lookin at a truck the other day and it was a 03 gmc with a 5.3 and tha guy that had it said it was a 5.3 h.o. and reason being is because he said it had an aluminum block and crap like that. Thats wasnt the first time i've "heard" of those trucks of having an alum block in them. my bestfriends dad had one tha same yr model and it was totally factory cuz hes old and doesn't care bout fast and he said his had an alum block and everytime me and my friend took it out there wasn't another factory truck intown like it that could hang.... SO i was wondering what yalls thoughts are. thanks

 

yep. aluminum has i think 30 more hp

 

Maybe I'm wrong, but I didn't think the L33 came out till 05...?

 

here we go again

yep some 05-06 ecsb 4x4s

Search L33 if you want to find some more info.

 

yup i thought 05-07 classic ecsb 4x4 could only get it. i got it haha

 

HERE IS THE ANSWER: ONLY 2005+ Z71 ECSB 5.3L had the Aluminum block L33. 8th digit in the vin is a "B" that is all, carry on.

 

Yeup...he's right again...


L33 5300 5.3

The L33 was an aluminum block version of the LM7, and was referred to as the Vortec 5300 HO in marketing materials. Horsepower increased by 15, to 310, over the LM7, and torque was unchanged. It was only available on extended cab 4WD pickup trucks.

Wiki'd

 

thanks guys

 

It's NOT ONLY Z71's, it is 2005+ ECSB 4X4's. I have the L33 engine and my truck is not a Z71.