tow rig question?
 

How much would i be able to tow with a 1992 GMC 3500 dually with a 5.7? I found one pretty cheap with fairly low miles. But if i move up to a bigger boat i'm not sur eif the 5.7 is gonna be enough.

Depends on how hard you want to work the truck. Since its a dually, it already has got a good rear end, and the 350 chevy is a tough motor. They'll run forever(and I'm a Ford man).

reasonable to pull 38' ?

Puder,
I do not know a rating for that truck. Try posting your question at Pickuptruck.com. I am sure they can help you.

I have the 5.7 in a 1996 Tahoe. Given the dually 3500 frame has more shear strengh capability than my frame does, and suspension and braking, but the 5.7 in the truck you mention has approximately 40 less HP than mine, as in 1996 they went to the Vortec setup. I tow my 26' Sonic at 7280# with trailer, fuel, and gear included. My truck is rated for 7000# maximum. I would not want tow anymore weight with the motor/trans./gears that I have. What gears does the dually have? That plays a big part.
Hope this helps.

A 38's gonna be over the top for the 5.7....It will do it just not for long!!! hold out for a 454...

You will NOT be happy with the pulling power of the 5.7. I pulled my 24 Outlaw(6500# loaded with fuel and gear)with a 1500 with the same engine and it was tough going up any big hills. Also the 3500 is a lot heavier truck and takes more power just to move the truck. I currently have a 93 3500 dually CC with a 454 and 4.10 gears and would not tow a 38' anything with it for any considerable distance.

Can always upgrade
 

I pretty much agree with all that's been said. A lot depends on how far you will tow- if it's a 15 mile run from boat storage to water what's 5 extra minutes?

If you plan to visit far away waters you will likely be frustrated. If the truck is a swinging deal though you could always swap in an injected 7.4 or GM even has a 502 tow motor package. Don't forget our buddy Mr. Whipple, You'd get the big block performance or better and it is hard to kill a 350.

If you plan on covering a lot of distance you should consider holding out for a Diesel- there is no substitute. GM's diesels are generally regarded as underperforming junk (relative to the Cummins or Powerstroke) unless you are talking Duramax and those aluminum heads are relatively unproven reliability wise. I'm sure there's plenty of people happy with their olderv GM diesels but they've likely not compared towing performance with the other two.

Gotta agree the older GM diesels are junk......unless you need a new anchor ? Heard a couple problems with duramax heads...Friend at a dealer told me GM said any motor problems pull them out & send them back to GM. sounds like they are on top of things this time!?

Actually if I remember correctly,,, they were rated to tow the same,,, 350 vs 454,,, back then when I was looking at duallys,,,, I couldn't believe it,,, I would have to check, but I think it was rated at 10,000lbs,,,,, might not be happy,,, but I think thats what it was,,, i'll look for the old brochure,,,,, I keep wierd stuff like that !! And if it's that great a deal,,, do a motor swap if your not happy like was mentioned,,, no big deal

Youre correct they are both rated at 10,000 lbs. But tow ratings dont take those "hill" things into account. also they dont say how long it will takr you to get movin.