700 needs rebuilt. What do I need?

[Scruffy]

First ever 700r4. 92 K1500 ecsb. 330hp crate 350 with tbi reinstalled by previous owner. LT285/75R16AT tires, getting swapped for mud tires.

Primarily a farm use truck, but, will be seeing some high speed highway use. If you can't do at least 80 in a 55 here, the tractor trailers will knock you off the interstates.

Current trans has a new tv cable. Fresh fluid, filter and gasket. Dire need for a new torque converter, the current one clanks like there is an anvil stuck between the flexplate and the engine block.

Transmission only works in R-1-2, tries to grab 3 but won't hold it. Truck will run as high as 65mph in 2, but I keep it on the farm for now so I don't blow anything up.

I'm going to need the truck "right" come harvest season, which is November through February for pecans and walnuts. We'll be towing an enclosed trailer with about 6 tons per load, 500 mile round trip to our preferred buyer. Truck does not have a stand alone cooler, only the one in the radiator.

I'm used to an 85 C10 4.3 4bbl/th400. Or a 69 Dodge D100 318/727. Only other modern automatics we have are in a 95 Outback and an 06 Vibe. So I'm a bit confused on where to start. Thanks in advance.

 

[michael hurd]

12K in payload, plus the weight of a trailer isn't a good idea with 1/2 ton truck like that. The transmission won't like that much at all, nor are the brakes capable enough ( even with the assistance of trailer brakes ) and the frame would be marginal in terms of strength.

K3500 would be a better start, even the 454 is only rated at 10K towing. You might even be better off considering a small single axle 3-5 ton truck to tow that.

 

[Scruffy]

I've got a couple jumbos I could use, but at 4mpg on a good day... 1987 C60 with 350/4spd or a 1968 D400 based motorhome with 413/727.

Don't mind cutting the load weight down.

I do need this truck fully functional. I'm only in it $500, new windshield and purchase price combined. New bed will set me back $100-300 depending on which yard it comes from. New front bumper is just time, already have all the metal, and the log for the red oak 6x12 or 8x12 push bumper (think circle track) is already down and ready to slab up.

Will do the body, paint and interior myself, I do those for fun anyway.

I need to know what to buy, or request be used, in a beefed up, heavier than stock application. I'd love to ditch the slushbox and put in a 5 or 6 speed manual, but, not in the cards. One of the farm users of the truck is pushing 90 years old, can't work a clutch anymore.

I have no qualms dropping real money on durable upgrades. I'd rather do it right, once, than keep paying for half fixes.

 

[michael hurd]

A stock 4L80 is stronger stock than a 4L60 / 700R4, even if you spend a pile of money in good parts for the 700 / 4l60. You can swap to a 4L80, and buy a stand alone controller, but it's still going to be expensive.

This is a video of the 3-4 clutch drum in a 700R4 / 4L60 with 110psi air pressure applied: Note how much the cover deflects, this tries to bend the clutches and steels in a cone shape.

https://www.youtube.com/watch?v=4fdMp1uOHz0

These transmissions just aren't made for all kinds of abuse.

 

[michael hurd]

Even if you ditched the 700, and installed a TH400 or a 4l80 with a standalone controller, you are going to be in it for a few bucks.

Here's a decent start... even the interior has the plastic on the seats. Arizona, low mileage, no rust or rot at all. Downside is the TBI 454, and the 4.11 ratio. It's only a plane ticket away, and fuel for the drive back.

http://www.ebay.com/itm/GMC-Sierra-3500-Extended-Cab-4X4-Dually-11K-Miles-/371338538176?forcerrptr=true&hash=item5675806cc0&item=371338538176