Lame duck

[gottaswapup]

Hi all,
Last summer I picked up a 2006 Sierra 1500WT RCLB 4.3/4L603/3.23:1 2wd w/ 47000 miles for $7700.
Having been repeatedly disappointed with it for most of a year now, I've been doing research, not just on here.
Part of the problem is the 3.23:1 axle with 245/70R17 tires. I'm amazed that a 4.3 can pull 1600 rpm @ 65 mph with this much vehicle attached. Back in '95 I had a new '94 WT1500 RCLB 4.3/4L60E/3.73:1 2wd 235/75R15 that always gave 23 mpg hwy, empty.
But this newer truck won't take any grade at all without at least unlocking the converter, and usually downshifting. So there goes the mileage. I'm convinced this new truck wants more rear gear.
Especially with these heads. The old swirl-port heads were done by 4000 rpm, but they must be better below 2000 rpm, and at least equal through 2500.
So, last August I hitched the new truck to a trailer and made a trip. I knew better than to tow in OD, so I didn't. Bu it ended up thast more than 50% of the trip was in weak second gear instead of strong third gear. It's hell having to drive in the gear you know is most likely to fail. By the way, so far I've killed 6 4L60s. It's always the band for second/fourth that goes first. Even with a billet servo.
I may swap in a V8, I have a 5.3 for it, but the axle will be first. Along with better rear springs. So I'll go start a thread about that.

[SLO TRUCK]

welcome to the site. You killed 6 4l60e's with a 4.3? Yeah you might as well swap in a 6.0 instead of the 5.3 if you are going to the swap.

[Z88 sd]

Welcome and good luck. BTW V6 in a fullsize truck WTF

[DUALLS]

Welcome

[ma.racing]

4l80e thats all i have to say

[Botlfed]

4l80e thats all i have to say

[GasGuzzler]

Welcome. My 6-cylinder 60E has 212K miles.

[gottaswapup]

Thanks guys.
No, 2 of the 60Es I killed were in my '95 Z28. One was in my '83 C-10 diesel, it wasn't an E, it was just a 700R-4, now called the 4L60. One was in my old '89 S-10 4.3, it had 282,000 miles on it.
But I found a sure cure for this basic transmission. A place much cheaper than FLT, but surely as good. I got one of their level 2 units used, and have proceeded to add 170,000 trouble-free miles to it since, including a summer in an '88 IROC-Z that ran low 10s at the dragstrip.
I'll be sending them this 60E if it ever fails.

[f4tal]

Thanks guys.
No, 2 of the 60Es I killed were in my '95 Z28. One was in my '83 C-10 diesel, it wasn't an E, it was just a 700R-4, now called the 4L60. One was in my old '89 S-10 4.3, it had 282,000 miles on it.
But I found a sure cure for this basic transmission. A place much cheaper than FLT, but surely as good. I got one of their level 2 units used, and have proceeded to add 170,000 trouble-free miles to it since, including a summer in an '88 IROC-Z that ran low 10s at the dragstrip.
I'll be sending them this 60E if it ever fails.

and who might they be??

[gottaswapup]

Oh, sorry, kinda left that out, didn't I.
BowTie Overdrives. They not only dyno every trans before shipping, they also install each one in a car and drive it. Their level 3 and level 4 versions are rated to 620 ft-lbs. PlaceHolder for 700r4.com ,iirc.