new gmt400 owner with towing question.

[tloh]

Hey everyone, I have a long bed extended cab 90 lo5 5.7 4x4 gmt400. I got this truck from a family member with a bad piston, recently rebuild the 5.7 and been using it for a shop truck. It has the 700r4 transmission in it as well. My question is what is the towing power of the lo5 5.7?

Reason I ask is, I recently went on a 5 1/2 hour drive picking up a motor/transmission. The gmt without the drivetrain in the bed was cruising low rpms around 75-80 easy, but with the load it was a struggle getting it to cruise comfortable at anything above 75mph rpm wise. I have a dual axle flat bed I tow a 2800lb car with. I am wanting to use the gmt as a go-to tow truck for this trailer instead of the cummins I am trying to sale. Is the lo5/700r4 up to that, or should I be thinking about finding a lq9/4l80 combo before I try to tow that kind of weight with the gmt? The trailer will need towing as much as 5 hour tow periods. Love the truck though, it's def grown on me after working on it. First post, so hopefully I didn't break any forum rules and posted in the right spot.

 

[east302]

From the factory, maximum towing capacity was probably in the 5,000-6,500 lb. neighborhood, depending on the rear axle (3.42, 3.73 or 4.10). I would assume that you're just under that with the 2,800-lb car plus whatever the trailer weight is.

A 6.0L would definitely help with acceleration, but wouldn't necessarily increase your safe towing capacity...it's the braking performance that I'd be more worried about.

 

[poncho62]

I tow a small 5th wheel (6000lbs) with my 97 K1500.....3.73 gears, tow package

If you are going to tow with your truck, make sure it has an external tranny cooler, install a trans temp gauge and tow in 3rd gear, not overdrive.

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[tloh]

thank both for the comments. Didn't know about the leave it in drive thing. I def need to buy a transmission cooler because I hate when its a rad/cooler combo anyway. also what's the thoughts on daul e fans running none stop versus the stock clutch fan system? Still running clutch fan + shroud.

 

[94_C/1500]

The 350 is fine, if yours is operating properly. I've hauled over a ton a few times with mine, and it's a V6. It doesn't struggle at all. I also keep it out of overdrive and baby it when there's a load in it.
I just hauled 2600 pounds in it last week.