transmission with overdrive.

I am looking for an adaptor plate for a 225 leaning tower of power, so I can bolt up a newer transmission with overdrive. ?

You can always add a Gear Vendors overdrive unit , you may have to get a second mortgage on you house  . I know that some of the slant sixes had a transmission adapter plate. But am unsure it you could cross it to a late model V8 overdrive. The only other overdrive for the /6 was a manual used in the late 70's (volare etc) . But shift linkage would be a problem .
There is a company call Wilcap.com that sells adapters for the old mopar flathead six cylinders, but the are not cheap. Good Luck

With the adapter plate you could mount the 518 (46RH) trans, build a new hanger bracket, depending on the year model a new torque converter, possibly a flex plate, a switch to lock the overdrive out, will have to be a 95 and earlier after that the 5i8 (46RE) became computer shifted don't go there.

In the end you will be locked out most of the time, the /6 just doesn't have the whoopie unless you plan on modifying it. Go find a nice 904 with lockup from around 1981- later, has wide gear set and steel planetaries, you may have to snag twp, one a /6 the other a V8 model to get the good stuff out of it or have the 904 built with those goodies. In drive while cruising the rpm's will be lower and 1st will launch you quicker.

Wilcap makes an adapter so you can hook it to a GM transmission which really opens up the options. I think the 200-4R would be a great compliment to the slant.

http://www.wilcap.com/225350.PDF

WYO George wrote:Wilcap makes an adapter so you can hook it to a GM transmission which really opens up the options. I think the 200-4R would be a great compliment to the slant.

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ttp://www.wilcap.com/225350.PDF

I used a 200-4R in my 46 Dodge pickup with a SB chevy. I loved that transmission. And the 200-4R was used behind those Buick Grand nationals V6 turbos Guys build them up to handle like 500 or more horsepower.

I have a dodge? A100 I will check with willcap and see thank you.

Be ready for sticker shock!  I'll bet the price is $600-800 plus shipping. and you may need to buy some pats. Good Luck.
Also when installing a 200R4. You MUST make sure that the TV cable is adjusted RIGHT. If not you can easily mess up the transmission.
You could just buy a different rearend center section. And get some Highway gears. Like 3.23/2.94/2.76 that's what I'm doing. Cheaper and easier than trying to install a overdrive transmission. You can usually pickup a center section for under $100.00 (non- posi).
The biggest down fall of using a set of Highway gears, is that your lowend/takeoff power is not as great. But at highway speeds your RPM would be lower, and you gas mileage "should improve" results may very.

This is a bit "quick and dirty" but have you thought abut simply fitting taller rear tires for when you want to cruise the Highway?

You could experiment with some used tires to start with and if the idea works get some quality tires for future use.

If you do some calculation beforehand you can work out how much height increase will change your gearing.

This would be cheaper than a centre section and way cheaper than any trans swap. Plus you don't get under and get dirty doing it.

It also leaves you with the same around town performance you now have with easier cruising with just the tire change.

By installing rear tire that are 1" taller, you would only reduce your cruising RPM by aprox only 100 rpm. And also anytime you go to taller rear tire "it will effect your around town performance" Because any tire diameter change will effect ALL performance through out the entire driving usage, lowend take off power and high speed cruising rpm.They will all be effected, just as with a gear ratio change.
By changing from a 3.55 to a 3.23 your crusing RPM would lower about 145 RPM. Considering your using the same size tires.
Your right that a tire change would be easier..if you install a tall enough rear tire. You would need to go at least 1.5" taller in DIA. to equal a one step gear ratio change.
I've done a lot of research on this. You can go to Summit.com and use there gear ratio/rpm tool to get some idea of what works best.
Also when changing rear tire diameter OR gear ratio, you will need to change out the speedometer gear(easy&cheap). Because your speedometer will not be correct.

I'm aware of the implications of changing tire diameter and that's why I suggested it.

Cheaper than a diff centre change, MUCH cheaper than a trans change, easier to swap back and forth and it would be a good test of what a centre change would do for you with spending big bucks.

As for speedo gears I don't own a car with a carb or speedo cable.

I was just trying to explain how tire diameter, and or gear ratios effect RPM, for guys that don't know much about the subject. And I'm sure that most guys with A100's are still using a mechanical speedometer.