Turbo 350 to overdrive

[Scotty D]

I’m thinking about replacing my Turbo 350 with an automatic with an overdrive or a lock up torque converter.
Only thing is that my 1979 C10 (2 wheel drive) has no electronics or computer, I know guys do this all the time, but how do you do this and control the overdrive?

 

[idahovette]

700R4 is manual cable operated. Hooks to your carb with the proper kit.

 

[Matt69olds]

The 700 needs no electronics. The converter clutch is cheap and easy to make functional.

The TV cable is critical, it HAS to be right.

 

[CountKrunk]

I have a turbo 400 and I'm going to just go straight to 4l80e eventually.

It uses a standalone controller to make it operate.

Mates right up though.

 

[NickTransmissions]

I’m thinking about replacing my Turbo 350 with an automatic with an overdrive or a lock up torque converter.
Only thing is that my 1979 C10 (2 wheel drive) has no electronics or computer, I know guys do this all the time, but how do you do this and control the overdrive?

Build up a 700r4, late unit (87-92). If you can find an 87 unit specifically, you can control the torque converter 100% mechanically via the TCC shift valve location in the valve body using Transgo or Superior Tech’s TCC mechanical lock up kits. You can install any 1982-87 valve body onto any 1988+ 700r4 as well.

 

[Scruffy49]

Have a reliable shop go through your core, or build it at home. The local shadetree guy -WILL screw it up. Take your time, follow Nick’s build guide/instructions, and DO NOT use a “universal” TV cable.

My now parts roach (frame rot) 1992 K1500 has a tbi 350 and 700r4. Marine intake, so a stock tv cable is too short. Service life with the “universal” cable was anywhere from 8 weeks to no more than 8 months between rebuilds (under warranty). It also had a habit of snapping flexplates. Buy an SFI approved flexplate if you want it to hold up. Buy and run a cast aluminum pan, helps keep you from damaging the pan gasket from overtightening. Jegs has fancy, that means expensive, reusable pan gaskets that are worth every penny spent on them. So is a pan stud kit…

If you build it right, well worth it in a 2wd.

 

[Jason in KC]

Although pricey, you could also look into a Gear Vendors overdrive.

 

[shovelbill80]

I'd also make sure a good transmission cooler was on the list for the conversion...

 

[shovelbill80]

Although pricey, you could also look into a Gear Vendors overdrive.

I had one in a '78 Camper Special some years ago...

Holy cow...prices have gone up a bit:

Automatic 3-Speed T-350 6" Tailhousing - Gearvendors

Automatic 3-Speed T-350 6″ Tailhousing.Replaces 6″ tailhousing.TH350 Short most common on the 350 series.

gearvendors.com

 

[CountKrunk]

I had one in a '78 Camper Special some years ago...

Holy cow...prices have gone up a bit:

Automatic 3-Speed T-350 6" Tailhousing - Gearvendors

Automatic 3-Speed T-350 6″ Tailhousing.Replaces 6″ tailhousing.TH350 Short most common on the 350 series.

gearvendors.com

No kidding! Could rebuild a 4L80e and grab the controller for most likely less haha.

 

[shovelbill80]

No kidding! Could rebuild a 4L80e and grab the controller for most likely less haha.

I think that's the route I'd go...
Over the decades, I've had a few 700Rs, a 4L60E, and now a crate 4L70E in my '98. Not mentioning the 350s and 400s.

 

[Craig Nedrow]

Just bought a 700r4, it's down at the shop I use. The later ones have the 30 spline instead of 27, it is replacing the TH400. I have a 4l80e but it needs a controller, and my 85 with the 6.2 dezel had the option for that year. You will/may have to cut the drive line, shorter, (I think about 2 inches?) and I will replaes the 32 spline with a 30 spline on the drive shaft.

 

[Ricko1966]

There were three different tailshaft lengths,for turbo hydro 350. Your truck should be a 9 inch. The difference in length is about 5/8th inch,there's a pretty good chance your driveshaft will work.

 

[Craig Nedrow]

There were three different tailshaft lengths,for turbo hydro 350. Your truck should be a 9 inch. The difference in length is about 5/8th inch,there's a pretty good chance your driveshaft will work.

Thank you Rick. I am good friends with the owners of PAC Trans in Yakima where I do business and Brian the owner has an impressive storage of old transmissions tail shaft and etc. down there. He has one so I’ll check out my transmission crawl under there. See how much space I have it would be nice in any case. I will do the driveshaft myself. I don’t trust anybody else…