The Stovebolt Site Forums The Shop Area Driveline MY6 to 235

Next week I will pick up a 54 Chevy pickup with original--or at least period correct-- driveline. I plan to swap in an MY6/ A833 transmission and lower ratio rear. Twenty years ago I put such a trans behind a SBC and it was a direct bolt-in. The trans I have now has an unusual bolt pattern, not typical Mopar or GM, and I suspect it will not be as easy. Note also the short tail shaft which will need a shifter with shorter rods than I normally see. When searching for adaptors and instructions what do I call this?

What model truck? The drive train between the 3100 (1/2 ton) and 3600 (3/4 ton) are substantially different. I realize that doesn't reply to you question but I think it is important to the end result you are aiming for.

treegrower - The GM "MY6" overdrive transmission is designed to mount directly with a standard GM/Chevrolet bell housing pattern. The pattern of your pictured transmission looks like the "A833" MOPAR version of the transmission, which only fits MOPAR bellhousings I think. The short tail shaft/housing is what clues one in that it's a truck model as most of the car model A833's had a long tail shaft/housing design.

On the shifter, from what I know of the MY6 and A833 truck units, used a specially designed shifter and rods. You might be able to use an aftermarket shifter and fabricate the needed rods and levers.

Here's a thread in another forum that has some great pictures and info on the A833 4 speed shifter and linkage. Below are a couple pics from that thread extracted from a MOPAR shop manual that show the shifter on the truck style short tail shaft transmission.

If you are hunting for an original style shifter, look at ebay. There are some offered, but be forewarned you are probably going to get some sticker shock on the asking prices.

This is a New Process transmission, it was found in GM Trucks and Step Vans from '80 -'87. It's pretty much a direct swap.

Agreed Craig about it being a New Process (NP440) transmission. My memory bank forgot that there was actually a dual pattern Chevrolet bell housing (I confirmed through a little web surfing), as there were evidently two different transmission bolt patterns depending on what transmission is involved. There was an aluminum case MY6 (NP440) that I have seen coming with the standard GM transmission mounting pattern and a cast iron model that used the MOPAR style mounting pattern.

Below is a screenshot from another forum that shows the "dual pattern" set up on a GM bell housing.

With that being said, treegrower - do you have a bell housing to match your "MY6/A833" transmission???

I’m running the MY6-A833a overdrive transmission in my 49 suburban. It’s a GEM! Don’t confuse the NP440 with the MY6-A833a. This is a light duty unit and is very easy to install.

You can use the stock 47-53 bellhousing but you must turn down the front bearing retainer on the MY6-A833a for it to fit. After that it’s time to figure out your rear end driveline set up ect. The shifters are hard to find, but EBay is a great source. I don’t recall having issues between shorter or longer rods when searching. I got lucky?

Once I found a good shifter core I sent it out to Hurst and they rebuilt it. Well worth the price and it’s tight and accurate. The shifter location is further back than the stock SM420 location so you’ll need to cut a hole and plan accordingly for your shifter arm. I had one custom made to Sorda look like a SM420.

I highly recommend this upgrade and love having the overdrive.

And yes, Treegrower, that’s not the correct MY6-A833a for our trucks, you have the Mopar version In the photos you posted.

Thanks for the responses. My further research shows this to be a hybrid between the usual Mopar and GM bolt patterns. It needs a bellhousing drilled to accept both this or the usual GM pattern. I found one on ebay, but cannot copy the photo. Challenge du jour is that the bell does not have the bottom flanges that are the rear motor mounts for the 235. Logic suggests an adaptor plate attached to the 235 bell would solve the problem, but what about input shaft length?
BTW the truck is a 3100. As an aside, it has a torque tube drive shaft, but the Factory Assembly manual and shop manual both call for open drive shaft. This has no impact on my plans, but is a little puzzling.

treefarmer - For your '54 3100, the torque tube setup is what it was equipped with per the 1954 Chevrolet Truck data PDF found in the GM Heritage Center archives. See the screenshot below. Models 3600 and up had open style drive shaft setups. Both setups are shown/described in the Shop Manual and FAM, but are listed for the models numbers applicable.

On the specialty bell housing to adapt the transmission you have, it does bolt up to a SBC and the 1963 and later design in-line 6 engines, but will not bolt up to a 1962 and earlier 235/261 engine. Are you planning an engine swap in addition to the transmission? If so, you will need to definitely make changes in the current rear engine mount/cross member set up to support the change.

Good luck with your project.

Gdads--thanks for the feedback. It is a little difficult to make firm plans and commit to $$ outlay without the truck on hand--hope to get it this week. I really do not want to swap engines if not necessary. If this trans is too odd to adapt to the 235, I have a Ford T170 on hand, and if that is too challenging I can do a T5. As I discovered when I had a T5 behind a 350 ( https://www.stovebolt.com/gallery/reay_russell_1957.html) the gear ratios are too important to be left to chance, so I prefer a 4speed OD. I just saw a Youtube video showing a 53 Chevy engine receiving a T5, and noted the bell/ rear motor mount is different from that shown in the shop manual.

treegrower - Curios to know more about your reference to "Russell" Reay's truck??? Is that just a similar setup to what you had, or perhaps it's your truck???

That was my truck

Cool bit of Stovebolt history. Thanks for sharing!