Manual tranny interchange possible? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Michael A. K. G · 07-31-2002, 01:14 PM

Hi folks.

I have a recently acquired '72 C-10 with a 3speed manual (Muncie, I think) and a column shift, behind a 250cid inline six. It has the integral low hump.

Is it feasible to replace this with a 4speed and regear with a lower (numerical) ratio in the diff, to approximate an overdrive? I know I'll have to cut a hole in the floor for the stick; my main question is, what about driveshafts and clearance. The one four speed I found in the junkyard was much more "boxy" than the 3speed I currently have; it has no tailshaft housing (and it was in a Chevy Van). Will it clear the low hump? Are there driveshaft issues?

This particular 4speed was also behind a 250cid inline six, but can I take a 4speed from behind a small block V8 instead? Or should I just take the small block with it (big sale on engines at this junkyard -- $70 including accessories and flywheel, assuming you can find one in one piece)? What would be a good displacement for mostly highway/mountain driving and light hauling (I don't need massive power, just decent, and ok gas mileage would be a plus).

TIA.

Longhorn Man · 07-31-2002, 05:05 PM

Being that you have an inline 6 in your ride, I think I would look for a T-5 tranny out of a camaro. It will hold up to your motor, and you'll still have your pullin power, and an overdrive for the freeway.

Michael A. K. G · 07-31-2002, 05:55 PM

Well, that sure does sound simpler.

T-5s were used in Mustangs, too, weren't they? Different bellhousing?

I presume it's a different length than stock, so a custom driveshaft would be needed, right? Is it longer or shorter?

And I presume I still have to cut a hole in the floor. Or was there a column shift Camaro (or would that be just stupid in a sports car)?

Hey, thanks.

Longhorn Man · 07-31-2002, 05:57 PM

Mustang...don't even try it. If memory serves, it's more troule than it's worth.
The S-10s had it too, but it was weaker.
Yes, a hole in the floor, plus, fabbing a shifter that would not come up inder the seat maybe(not sure bout that)

Michael A. K. G · 07-31-2002, 06:16 PM

Correct me if I'm wrong, but wouldn't the tranny have to be outrageously long (and have a far-back shifter) to come out in the seat in this truck?

If memory serves me right, the clutch is more or less right at the firewall.

Fabbing a shifter is not something I'm sure I can do. I've never done it before. Are there adapter kits or do I get to spend big bucks having one fabbed by a machine shop?

Or do I just get one from an S10, since that already IS a truck? Can the guts be interchanged (I do have a press, splitter, and a homemade long-reach bearing puller, if needed)?

By "weaker" do you mean it breaks more easily, or has worse gear ratios?

07-31-2002, 01:14 PM	#1
Michael A. K. G Registered User Join Date: Jul 2002 Location: California central coast Posts: 126	Manual tranny interchange possible? Hi folks. I have a recently acquired '72 C-10 with a 3speed manual (Muncie, I think) and a column shift, behind a 250cid inline six. It has the integral low hump. Is it feasible to replace this with a 4speed and regear with a lower (numerical) ratio in the diff, to approximate an overdrive? I know I'll have to cut a hole in the floor for the stick; my main question is, what about driveshafts and clearance. The one four speed I found in the junkyard was much more "boxy" than the 3speed I currently have; it has no tailshaft housing (and it was in a Chevy Van). Will it clear the low hump? Are there driveshaft issues? This particular 4speed was also behind a 250cid inline six, but can I take a 4speed from behind a small block V8 instead? Or should I just take the small block with it (big sale on engines at this junkyard -- $70 including accessories and flywheel, assuming you can find one in one piece)? What would be a good displacement for mostly highway/mountain driving and light hauling (I don't need massive power, just decent, and ok gas mileage would be a plus). TIA.

07-31-2002, 05:05 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Being that you have an inline 6 in your ride, I think I would look for a T-5 tranny out of a camaro. It will hold up to your motor, and you'll still have your pullin power, and an overdrive for the freeway.

07-31-2002, 05:55 PM	#3
Michael A. K. G Registered User Join Date: Jul 2002 Location: California central coast Posts: 126	Well, that sure does sound simpler. T-5s were used in Mustangs, too, weren't they? Different bellhousing? I presume it's a different length than stock, so a custom driveshaft would be needed, right? Is it longer or shorter? And I presume I still have to cut a hole in the floor. Or was there a column shift Camaro (or would that be just stupid in a sports car)? Hey, thanks.

07-31-2002, 05:57 PM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Mustang...don't even try it. If memory serves, it's more troule than it's worth. The S-10s had it too, but it was weaker. Yes, a hole in the floor, plus, fabbing a shifter that would not come up inder the seat maybe(not sure bout that)

07-31-2002, 06:16 PM	#5
Michael A. K. G Registered User Join Date: Jul 2002 Location: California central coast Posts: 126	Correct me if I'm wrong, but wouldn't the tranny have to be outrageously long (and have a far-back shifter) to come out in the seat in this truck? If memory serves me right, the clutch is more or less right at the firewall. Fabbing a shifter is not something I'm sure I can do. I've never done it before. Are there adapter kits or do I get to spend big bucks having one fabbed by a machine shop? Or do I just get one from an S10, since that already IS a truck? Can the guts be interchanged (I do have a press, splitter, and a homemade long-reach bearing puller, if needed)? By "weaker" do you mean it breaks more easily, or has worse gear ratios?



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