C10 3 speed transmission question
 

I'm in the process of planning a restoration on a 67 C10, currently with a V8 (non org 350), and 3 speed manual on the column. Question is......Was a 3 speed manual with overdrive offered as a factory option in the 67-72 C10s? If not, is there such a transmission from any other GM vehicle that would work?

No OD trans were available for the Chevy trucks in '67-'72. Lots of folks here have done trans swaps and can offer good advice. If your interested in an auto OD 700R4, 2004R, 4L60 and 4L80's all will fit with some massaging. Welcome!

Sweet72.............I think your wrong on your observation. Owners manuals show the ratios in each gear and a 3spd with OD was listed in manuals.

I think there was an overdrive unit on the 67 and 68"s. It was on option on the 3 speed manual. It sat behind the trans. Very rare.

Is there an OEM manual with O/D that will work? Yes. The question is how much work you're willing to put into it to make it happen.
The O/D tranny's that come in Camaros, Vettes and late model trucks will bolt right up to your bellhousing but they could require different crossmembers and definitely require resized drive shafts.

Yes, there was an overdrive tranny. However, it is not of much value. Assuming you find one that works, you'll never get any replacement parts, and it'll basicly be a disposable part.
however, yes, there was a 3 speed manual with overdrive avalible with the inlines and the 283 and 307 engines. It was sold under RPO M10. It included the 4.11 rear gear ratio axle and you couldn't get any other gear ratio. It was avalible from 67 - 69, and only in C/10 models.

wink05, just noticing this is your first post...
Welcom to the board from Central ohio. Many ppl here from your neck of the woods.
You should be able to find out pretty much anything you want to know about these old trucks on this site...just ask and you'll probably get 5 answers. :lol:
What's the details of your truck...any pics? We love pics. ;)

Thanks for the quick and valuable info.........first post, not the last, with this kind of help. Photos later, just a 1 owner, barn find (outside the barn, that is!)........C10 SWB all orig, lots of Texas sun on it. Again thanks to all for your time and help.

Wink

I thought I was wrong once, but realized I was only wrong in thinking I was wrong. ;) :lol:

Keep us posted if you do this swap! I would love an overdrive....

I had a 67 with the three speed plus overdrive several years ago. The option was listed on the glovebox door, and as Longhorn Man said, it had 4:11 gears. It did get me as much as 21 MPG on the highway with a stock inline 6 engine, but I got greedy for power and got lazy and tired of shifting, so I swapped in a V8 and an automatic transmission.

How was it engaged? I heard somewhere that there was a pull knob on/under the dash that was pulled, then you let off the gas it would engage, then be on until you pushed the knob back? Did it work well for you or was it a PITA?

I suspect that originally there may have been some sort of governer or something that assisted in shifting it, but if there was, it was long gone by the time I got the truck. There was a cable-actuated lever on the side of the overdrive unit, as well as an electric solenoid. The cable was activated by a nice chrome T-handle that was mounted to the bottom of the dash and said "OVERDRIVE" on it in large text. Pushing the handle in put the transmission into a freewheeling mode where the engine would go down to idle if I lifted my foot off the accelerator when I was driving down the road. There was a pull switch on the dash that activated the solenoid. The solenoid would engage the overdrive gear. I'd have to let off the gas and turn on the solenoid simultaneously, and once the engine RPM dropped the correct amount, the overdrive gear would engage with a CLUNK. I used it all the time because it got me better gas mileage, but it was a PITA. There were two things that bugged me about it. One was that if I didn't turn on the solenoid at exactly the right time, the overdrive gear wouldn't engage, and I'd blow out the solenoid fuse. The other annoyance was that if I forgot to turn off the overdrive, and came to a stop, I couldn't disengage the overdrive until I was moving again, and it would make 1st gear more like second, so it was a bit difficult to get going again. I definitely prefer the 700R4 transmission I have in my truck now, even if it isn't the most robust transmission ever made. It only cost me $65 at the local pick-n-pull wrecking yard and many hours of my own time (I like working on my truck anyway), so I'll enjoy it while it lasts.

There was a 3-speed with overdrive transmission option on our trucks. It was the saginaw 3-speed with overdrive. The main shaft and main case are interchangeable with the saginaw 3 speed and saginaw 4 speed transmissions. The overdrive unit was internal to the transmission. It was housed in a modified saginaw tail housing. I think they used a governor to tell it when to kick-in. There was the cable control, that basically locked out the over drive from kicking-in if you did not want to use it. There was also a soloniod control that was hooked to a carburetor kick-down switch. Also called a detent switch. In the mid 1970's Hot rod magazine published an article about making a saginaw 4-speed with overdrive transmission, from a saginaw 4-speed and a saginaw 3-speed with overdrive tail unit. Since the main case and the main shaft were interchangeable, it could be done. I actually did this myself. I had alot of fun with punching the trottle on the freeway and having it automatically kick down to 4th gear. The saginaw 3-speed with overdrive is out there, but I have not seen it much in the self-serve junk yards. But I bet collectors and trans shops have them. Hope this helps.

i have a saginaw 3 speed transmission.

Bruce68SB is almost correct on the applications..they also come in the mid sixties chev cars too but are fairly rare) and totally correct on the conversions using the Saginaw 4 speeds and the overdrive off the 3 speeds to make a 4 speed overdrive.. they are a blast to drive.. it is an easy coversion I have done several over the years.. Keep looking they are out there....