Old school install

[Pilothouse]

Looking for some opinions and advice. I have a 1948 Dodge B1 1/2 ton pickup which sits on a 1987 Dodge Dakota chassis. The 3.9 liter v-6 is underwhelming in many ways, bad mileage for a v-6 and low on power as a light tow vehicle (small retro travel trailer) I am seriously considering a Cummins R2.8 install and am curious what those of you who have first hand experence think about the following:

Is the R2.8 a good fit for this application?

I would want to use a 6-speed or 8-speed auto trans, preferably a Chrysler 545rfe or 65rfe 6-speed or maybe a ZF 8HP70 8 speed. I wouldn’t rule out a GM trans as I have read about it being used successfully. Opinions?

thanks in advance for any input.

[RePowerToy]

Sounds like a fun project, I vote do it. I think a r2.8 would be a good fit. I personally think GM 6 speed is good, personally 8 speed works well in some vehicles but not all.

[DieselJeep]

I'd love to see some pictures. I'm not familiar with that truck, but the R2.8 is a great engine for a very diverse range of vehicles. It seems like cars to 1/2 tons it's hard to go wrong.

[Pilothouse]

In 1948 Dodge used a flathead 6 cyl so the in-line R2.8 would look right at home.

i mentioned the ZF 8 speeds because I have owned or driven 3 vehicles equipped with one and they all worked very well, especially when mated to a diesel. Problem is I don’t see where anyone is making a TSU for it?

[DieselJeep]

I was completely scared off of using an auto, but they make so much sense. If something happens to my trans, I'm going to put in an auto if I can afford it at the time. I've heard of the 8 speed mated to these and I assume they would have made them work.

There's starting to be more shops that have played with these engines and various transmissions. Maybe call up Axis or some others and see what kind of advice they've got. I've only owned maybe 2 or 3 vehicles with autos in my life so I'm pretty ignorant.

Of course, the R2.8 would likely be perfectly fine with the 6 speed. There's a pretty good power band on this engine, but I wouldn't typically want shifts to end up below 1500 rpms. I don't know the gearing, but I've heard some of these transmissions just have multiple granny gears. For those transmissions, I wouldn't have much concern about those over a good 6 speed. At work we stick to 1 ton to 2.5 ton trucks and the more speeds the transmissions have the sooner we trash a transmission. I know that's anecdotal evidence, but it was reinforced so many times, we just can't go that route anymore. Let alone we never saw any improvement in mileage or anything for that matter. I might add that with these transitions we used to overload 1/2 tons and they would outlast the newer 1 tons with the same load, if the engine was fairly small and a transmission with a lot of gears was used to compensate. It may have just been an end to an era where only the better drivetrains of the older models were left and then there were growing pains for the newer stuff.

[GrimmJeeper]

While there's nothing inherently wrong with the Chrysler transmissions, or the ZF for that matter, finding adapters to get it to bolt to the back of the engine may be hard to come by. I'm not sure if the ZF already has an adapter for the mounting pattern the 2.8 uses. I have not heard of anyone making a Chrysler pattern adapter. The only adapters for an automatic on the 2.8 are for GM and AMC Jeep (i.e. the AW4 in the 87-01 Cherokee). And even then, I don't know of anyone who has gotten the AW4 to work. They mostly use the adapter for the AX15 and NV3550 that came in the Wrangler, which, by the way, wouldn't be a bad option if you want to go manual. Plenty of people driving the GM 4L60, 4L80, and 6L80. And, if yours is a 4x4 Dakota chassis, it's easy to get an adapter for the GM transmission to the Chrysler transfer case.

[Pilothouse]

Axis makes an adapter for R2.8 to gen 3 hemp which covers the 6-speed 545RFE and ZF 8-sped 8HP70 and were doing an r2.8 ZF 8HP70 build last year, I need to call and see if they can point me at the trans controller. On another note Foton is using the 2.8 cumins and ZF 6-speed from the factory. https://tunland.foton.co.nz/