Guy's I'm considering an engine+transmission swap in my 2003 2wd ext.cab It's presently a 5.3L/4L60E with 130K and 3.42 rear gears. I'm looking at a possible 6.0L/4L80E with 40K. What I wanted to ask is this: Is there a substantial increase in torque with the 6.0L for towing at highway speeds. Thank you for any opinions.
Mike

 

Yes there is, you may want to step up your gearing while your at it. 3.42 isn't ideal for towing to start with, but the 6.0 will help IMO.

 

Yeah, the 6.0 will be a huge improvement over the 5.3

 

yep, you will be satisfied. Plus the 4l80 will give you another 100 rpms on the highway. It has a little lower OD. I think the 60 is .70 and the 80 is .76:1

 

Do the swap. There is no replacement for displacement.

Swap to 4.10 gears, or at least 3.73.

 

Guys I appreciate the input. If I can get the pieces gathered up I guess I'll move ahead with the swap. Thanks again.
Mike

 

Here's my opinion having gone from 4.8L to 6.0L

The torque of the 6.0 in comparison to the smaller engine is amazing when you first feel it. When I was done with the swap I was on the highway with the cruise set to 80 mph and the 6.0 just pulled the truck up big hills effortlessly, you could feel the torque when the accelerator went down. No downshifting.

With that said, the "glory" of the 6.0 wears off fast. After a while it just felt like what should have come standard. The 4l80e will suck more power than the 4l60e, but it also has a better OD for towing than the 4l60e. I would retain your 3.42 gears. There is a significant decrease in highway gas mileage between 4.10s and 3.42s. I lost 3-4 MPG myself. BTW, that maiden highway voyage with the 6.0 netted 23.5 mpg with the 4.8 in the bed.

 

Thanks GMCtrk,I will have to keep the 3.42's. This is my DD and I really don't want to give up any more mileage than I have to.
Mike

 

I DD my truck, don't be scared of running higher gears. I still get ~20 mpg on the highway I'm sure.

 

3.73's are a nice compromise for a daily driver, but I must admit I wish I had 4.10's when I'm cruisin' around town. I'll be rocking my factory 3.73's when I do my LQ9 for a few years at least though, should make for a nice touring truck, as I will be making more frequent trips from NJ to Mass to visit my buddy and hit the Summer Nats...