The Quest For Overdrive . . .

[jjester6000]

Now that 'Ol Yeller has a half decent motor in her again, I REALLY want overdrive.

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Currently she's got a 250 I6, Saginaw 3 speed, and a 3:55 Posi. It's not too bad on the highway, but I'm planning on driving the piss out of this thing this summer and OD would be nice.

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I'm not made of money, so the truck isn't getting a T56, billet driveshaft, and a Ford 9 Inch for it. She's getting only what she deserves . . .

I'm capping myself at an even $1,000 for this whole swap. Though before anything, I gotta decide what transmission to go with.

I have one criteria for everything, I want to keep the original mechanical clutch linkage. It would also be nice if I didn't have to change out the driveshaft either.

My best choice would be a mid 80's GM A833 4SPD OD transmission. Those things are REALLY rare, and when they do come up, they go for about double my budget.

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Another choice would be a T5 out of a late 80's 4.3 powered S10. The downside to one of these is that I'd definitely have to shorten the driveshaft (which is about $300 to have done near me) and they are kind of weak transmissions for this application.

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My third option is kind of impracitcal, if I somehow found one of the super rare and elusive Saginaw 3 Speed Overdrive transmissions. It would literially bolt right in, and I'd even be able to use my original shift linkage with it.

But there's no shot that I'm ever going to find one of those . . .

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(I actually did though I haven't bought it yet).

 

[Ricko1966]

Are you 1 piece drive shaft or 2 piece?

 

[Ricko1966]

I think your best bet honestly,for budget,ease of install etc. Grab a t5 with bell housing,shifter,and clutch disc from a junkyard s10 with cable driven speedometer. As for drive shaft. Many times when I'm doing weirdo swaps, after everything is in place I measure front yoke to back yoke and spend a few hours at the junkyard measuring driveshafts. I can almost always find something that works after a ujoint swap. If you are 2 piece you can swap to 1 piece. You can also shorten your own,if you are taught how it's not as common sense as you'd think at first but very,very,doable for a 2" shorten which is what you will need. I can teach you it will be in balance if it was before and still be in phase. I learned from the drive shaft shop that I used to pay to do my when I was a teenager.

 

[DoubleDingo]

With 3.55 gears leave it alone.

 

[jjester6000]

Are you 1 piece drive shaft or 2 piece?

2 piece

 

[jjester6000]

I think your best bet honestly,for budget,ease of install etc. Grab a t5 with bell housing,shifter,and clutch disc from a junkyard s10 with cable driven speedometer. As for drive shaft. Many times when I'm doing weirdo swaps, after everything is in place I measure front yoke to back yoke and spend a few hours at the junkyard measuring driveshafts. I can almost always find something that works after a ujoint swap. If you are 2 piece you can swap to 1 piece. You can also shorten your own,if you are taught how it's not as common sense as you'd think at first but very,very,doable for a 2" shorten which is what you will need. I can teach you it will be in balance if it was before and still be in phase. I learned from the drive shaft shop that I used to pay to do my when I was a teenager.

I agree that the T5 is a pretty easy swap, I'm just a bit worried about longevity in this application. I want to tow a car if I have to, or load the bed of the truck up with scrap metal.

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I've abused that little Saginaw quite a bit over the years, I don't know if a T5 would hold up.

 

[Ricko1966]

I think youd be fine I had a friend with a T5 in a Mustang taking it to the strip regular blowing nitrous on it running 12s or 13s. And it lasted 50,000 Mike's the engine gave up at 60 or 65. Specs aren't that different than what you had,and.you aren't going to give it shock loads,or gave much horse power. We used to blow up saginaws with 307 Chevelles.

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[bucket]

I think youd be fine I had a friend with a T5 in a Mustang taking it to the strip regular blowing nitrous on it running 12s or 13s. And it lasted 50,000 Mike's the engine gave up at 60 or 65. Specs aren't that different than what you had,and.you aren't going to give it shock loads,or gave much horse power. We used to blow up saginaws with 307 Chevelles.

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Your friends T5, did it have some money dumped into it with upgraded parts? If not, you really gotta be easy on them to avoid breaking them.

I'd ASSume that running one in a full size truck that occasionally sees towing duty would be about the equivalent of running one in a Mustang that runs 12's.

 

[DoubleDingo]

The 250 with 3.55 gears is not enough power for overdrive. Are you going big block? If yes, it can push the overdrive. If not, your 250 will struggle pushing that truck along on any grades. Gear swap to 4.10 or 4.56 and the overdrive, but you'll be right back to same highway rpms. 3.55 is a great gear. I'd recommend leaving it alone. 2600 rpm at 70 mph is not bad. You'll get worse mileage if you lower the rpms with an overdrive because you'll need way more throttle.

 

[Ricko1966]

I decided rather than edit post 7 I'd just make another post,to make some corrections. For some reason I thought they made 4.3 S10s with World class T5s,hmm seems they didn't on S10s. Camaros and Firebirds got World Class T5s. You can make a world class T5 from a Mustang work on a Muncie/Saginaw bellhousing but it's not exactly bolt in You can use a jeep iron Duke Ford transmission bell housing or use a scattershield . V8 World Class T5 would be what you'd want. So that takes T5 out of cheap and easy. Instead of the WC T5s they upgraded S10s to NV3500 if I wanted a 5 speed for your truck I'd still be robbing an S10 for a transmission it would just be an NV3500, not a T5. .

 

[DoubleDingo]

I decided rather than edit post 7 I'd just make another post,to make some corrections. For some reason I thought they made 4.3 S10s with World class T5s,hmm seems they didn't on Camaros and Firebirds got World Class T5s. You can make a world class T5 from a Mustang work on a Muncie/Saginaw bellhousing but it's not exactly bolt in You can use a jeep iron Duke Ford transmission bell housing or use a scattershield . V8 World Class T5 would be what you'd want. So that takes T5 out of cheso and easy. Instead of the WC T5s they upgraded S10s to NV3500 if I wanted a 5 speed for your truck I'd still be robbing an S10 for a transmission it would just be an NV3500 not a T5. .

And then a gear swap to 4.10 or 4.56 so the 250 can operate at the same rpms down the highway, or swap in a big block to so the torque can be utilized at the lower rpms he's shooting for.

 

[Grit dog]

I decided rather than edit post 7 I'd just make another post,to make some corrections. For some reason I thought they made 4.3 S10s with World class T5s,hmm seems they didn't on Camaros and Firebirds got World Class T5s. You can make a world class T5 from a Mustang work on a Muncie/Saginaw bellhousing but it's not exactly bolt in You can use a jeep iron Duke Ford transmission bell housing or use a scattershield . V8 World Class T5 would be what you'd want. So that takes T5 out of cheso and easy. Instead of the WC T5s they upgraded S10s to NV3500 if I wanted a 5 speed for your truck I'd still be robbing an S10 for a transmission it would just be an NV3500 not a T5. .

Half tons came with NV3500s for a few years too. 88- I’m not sure maybe 92-93. I think at some point they swapped the half tons 5 speeds to NV4500s. I pulled a 4500 from a 6 lug truck once but idk it may have been a light duty “2500.”

 

[Grit dog]

@jjester6000 ya, OD would be nice but I think the usefulness will be very limited. Just due to the low power engine pushing it.
With a stock size 235 tire you’re theoretically right about 2900 rpm’s at 70mph. So realistically 3k rpm’s.
It’s all in what you are prioritizing.
Flat sea level bob tail OD will be of use.
Anything beyond that for grade, load, headwind, varying speeds like a curvy road etc will render OD of little to no use.
IMO trying to doo too much with too few of ponies under the hood.

 

[bucket]

Half tons came with NV3500s for a few years too. 88- I’m not sure maybe 92-93. I think at some point they swapped the half tons 5 speeds to NV4500s. I pulled a 4500 from a 6 lug truck once but idk it may have been a light duty “2500.”

Yep, and an NV3500 can be broken in a full sized, 2wd truck with a 4.3L V6 pushing it. Another reason that I suggested a T5 (world class or not) would be too fragile.

 

[Grit dog]

Yep, and an NV3500 can be broken in a full sized, 2wd truck with a 4.3L V6 pushing it. Another reason that I suggested a T5 (world class or not) would be too fragile.

Idk anything about T5s other than what I’ve read/heard.
But the NV3500, I’ve put through the paces as daily/towing/hauling. (Like towing 8-10klbs x country in the summer) Had over 200k on one and 100k on another as daily/commuter/work trucks/ the occasional heel toe clutch dump smoky burnout and never had an issue. Certainly never broke either.
But any old 25-40 year old used pick r pull transmission is suspect for condition and longevity until it’s known.