Slant six to five or six speed trans.

[Spudmaster]

I have been trying for several years to find a bellhousing, an adapter or some method of replacing my 4 speed with a modern 5or6 speed transmission. I have come across lots of “do this” or “do that” ideas on the internet, most would seem to be backyard sketchy **** conversions. If someone knows of a method of putting a new transmission onto a slant six that is done properly, I would love to hear about it. I have talked to all the companies who make 5or6 speed gearbox’s, but no one, as of October 2024 offers a bellhousing or adapter. I did find one place which said a bellhousing from a mid 80s truck slant six can be adapted using a custom made adapter plate between the bellhousing and transmission, but I could not find any details about that. So any help would be greatly appreciated.

 

[halfafish]

There is a well documented process for putting a T-5 five-speed behind a slant. It takes a slant OD bellhousing, and the adapter plate from Gill Welding. Search over on slantsix.org and there is a very long and detailed how-to for this swap.

 

[Professor Fate]

T-5 Bellhousing Adapter Plate For Slant Six | gillwelding

 

[halfafish]

And I found the article that goes over the swap process.

FAQ The Definitive All Of Your Questions Answered T5 T-5 5 speed To Slant 6 Transmission Swap Guide. - Slant Six Forum

 

[AJ/FormS]

IIRC,
somebody did an AX15

the ratios are;
3.83-2.33-1.44-1.00-.79od; the splits are what's good about it;
.61-.62-.69-.79 fairly close and getting progressively tighter, in each gear..
In an early A-body, with 24.5" tires, the /225 should be able to pull 65=2200, so the rear gear could be as low as 2.94s, for 65=2068
That would give you a starter gear of 3.83 x 2.94= 11.26, which with those small tires equates to 500rpm=3.24mph. Daymn that's nice; almost makes me want to detune my 367 to 150hp, lol, to not bust that AX15
With 2.94s your Roadgears would be;
11.26-6.85-4.23-2.94-2.32 compared to mine;
10.97-6.82-4.97-3.55-2.77 which I really like behind my 367.
Jus trynta be helpfull.

To fit the clutch, the input might be a lil short. I wouldn't let that stop me, I'd just splice a Mopar input to the Jeep/Chevy, at the right distance, then neck it down to fit the AX retainer,


and somebody else did a ChevyS10 trans, a T5. This unit has no BH on it so adapting it to a slanty/overdrive BH should be easier.
The Ratios are;
4.01-2.33-1.39-1.00- .78od with splits of
.58-.60-.72-.78 and with 2.76s this time, the roadgears are
11.07-6.43-3.84-2.76-2.15, and 65=1919rpm

 

[RustyRatRod]

It's a pretty simple swap, but you have to cut the floor tunnel out and make a new one. I have everything to do the swap on my 64 Valiant, Vixen. She anxiously awaits. lol

 

[MV8]

I have a plan to use a trans that has not been used behind a slant before. Still have not had time to source the slant yet for mock up of the adapters. No special consumable or rare parts to source if converting from an automatic. Requires a hydraulic master cylinder and electronic speedo.