olds 307 and 403

I am planning on a 4th gen V6 T-5 trans, ideal gear ratios for my 2.78 rear gears. I know where a low mile unit is, also WC but has the Ford bolt pattern where the bell housing attaches. Was it 67 to 70?

joe_padavano

The Dearborn three speed was first offered in the 1965 model year. The dual pattern bell was actually used through the 1977 model year, despite the fact that GM stopped using the Dearborn trans in the 1971 model year (the toploader three speed was used in the full size cars later than in the A-body cars). There are three different casting numbers for this bellhousing, and for the life of me I can't see any differences other than the casting number. These are 547975, 9778882, and 9785581. The '581 seems to be most common, but they are all identical as far as I can tell.


Be aware that the GM-version Dearborn trans used the Ford bolt pattern but a GM-spec input shaft and bearing retainer. A Ford-spec T5 will still need an adapter plate.

olds 307 and 403

JetsetW31 on the G body site used the 4th gen F body V6 trans with an Olds 350 in a 88 Cutlass. I am pretty sure those have 26 spline input, 27 spline output with a GM size bearing retainer, not 100% sure on the bearing retainer size but I believe the A body bell housing just bolted on the Ford pattern. Good to know any A body bell housing should work. I just need to figure out pedals, clutch engagement, speedometer and whether the shifter will clear the bench seat. The 3.75 first gear should launch hard as hell with the 2.78 gears and the .72 OD, 70 to 80 mph will be perfect.

joe_padavano

I have one of those F-body transmissions with the factory hydraulic throwout bearing that I plan to use behind the Rover motor in my 62 F-85 wagon. I don't know if the input shaft length or pilot diameter are the same as for "normal" GM manuals.

olds 307 and 403

Interesting Joe, I may ask for some measurements and pics. My understanding is the T-5 is a nearly direct swap for a TH350 6" tail transmission. I will need to make sure my driveshaft doesn't bottom out and the input is the right length as well. I think my 350 is actually set up for a manual trans, it has the Z bar hole and I think the crank is drilled for a pilot bushing. I assume a hydraulic clutch set up needs to be fabbed and I hope the shifter clears the seat with room to spare. I would also like to see what kind of speed sensor is used and how easy it is to swap over to speedo gears for a cable drive. I am tired of automatic's leaking somewhere and failing. I know the T-5's are not super tough but should live, especially a low mile V6 trans.

joe_padavano

There are at least three different shifter locations (Mustang/Camaro, S-10, and Astro van), and changing the tailhousing is easy on a T5. It is also easy to add a speedo drive gear while the tailhousing is off. There are a number of web sites that show this.

olds 307 and 403

Thanks Joe. I am really looking to make this car a driver, no track close by anymore.