Ive got a 1968 Chevy short wb half ton. It is currently being built, it is for lack of a better term going to be a 'Pro touring" style truck. Lowered, big brakes, big wheels, etc. I had originally bought a 6 litre Geniii style motor for it. I recently won a 91 3500 Cummins truck on Ebay for $2000. It has 135,000 miles. A great donor vehicle. I figure a slammed, classic truck with big rig sounds and lots of soot would be cool!! What am I getting myself into? Im no idiot, I can pretty much do anything so cutting, welding, fabricating, etc is not problem. With having a donor vehicle Im not thinking its going to be all that bad of a swap. Im thinking I will keep the suspension stock until the motor is sitting in the frame rails, Then I can see what I have and go from there. I know it will need some SERIOUS springs upfront, probably some BB springs. I was originally looking at a 5/7 drop. With that 1200lbs upfront who knows where the front end will sit. What do you all think?

 

My only consern would be the half ton alxe....can you say axle pretsel


if you when to one ton stuff it might live!

 

I understand that in stock form the Half ton axle wont cut it. Heck its an open rearend a one wheel wonder. But its a 12 bolt and with the right parts will live easily.

 

:cough: :cough: 9 inch :cough:

 

I here ya, I here ya, the 9" is a great rearend. A 12 bolt will hold up just fine. This is a stock Cummins Im swapping in, eventually I'll turn it up. For now it will have an intake a some good exhaust.

 

Take a look at:

www.Cummins-Conversion.com

There are probably a few guys over there that have done this swap.

As to the rear-end, Dana 70's can barely hold up to a stock Cummins.

I will give the twelve-bolt, or the 9-inch, about two weeks.

 

How do you get to that conclusion? I've never heard of an axle failure, even on engines pushing 300+ horsepower...

 

Contact/PM doznfire. He can answer all your questions as he has done something similiar. Here is his @ one of our get togethers.



Or this one.

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yeah, a 12 bolt will work. i didnt read your next post. a buddy of mine built a chevy w/ a 400 hp bbc and a welded 12 bolt. the truck would run 11's and he never had a problem

 

im sorry to stray from topic, but is there any chance you could post a link to the ebay auction that won your $2000 donor vehicle so we could all see what $2000 gets you in the world of first gen CTD's?

the reason i ask is because im thinking of unloading my $500 beater and hopefully making a silly profit

 

You might want to do some measuring. I planed the same swap in to my 71 3/4 ton 4 Wd and bought the donor truck to do it. My truck was a 292 six origanaly and figured a six for a six. I thought wrong. The Cummins has a good bit of length on the GM don't remember specifics but trying to cram the intercooler AC evap and radiator in the whole deal only left me the option of moving the firewall back. Just fixed the donor truck and love it. Wound up with another donor and might be able to do a non Ic this time. Jethrro

 

this one was from Tx. even cheaper .

http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT

 

A friend of mine stuffed a 5.9 Cummins in a mid-80's Chevy 1 ton crew cab. He used a 3 speed splitter plus an NP-435 tranny and it's quite the vehicle!

I'd definitely consider more rear axle. True some big blocks pump out some horsepower but it isn't horsepower that mangles parts: it's TORQUE! Ain't no streetable big block putting out Cummins torque numbers....puts new meaning into the word ouchie!

You'll need the GM-Cummins adapter plate [I've got a spare] which cants the engine about 10-15 degrees to one side. The Cummins eats even the built Pontiac TH400's for breakfast so better consider LOTS of tranny behind it. Most of the used breadvans or Frito Lay trucks used as donors for Cummins 3.9L 4BT swaps had TH400's behind them, and usually they're being dumped because the Pontiac TH400's couldn't even hold up to the 5.9's baby brother. SM465 can take the punishment and you get to play with gears more.

Clearances are VERY close stuffing one in, and you will likely have to massage the firewall [especially for the exhaust downtube] and look at shoving the radiator forward. Need electric pusher fan most likely, and plenty of radiator, but it can be done. Clean out the fuel tank thoroughly and run larger lines, plus a return line. Cummins wants more air, water and fuel than the stocker engines.

Enjoy yourself.......

 

I got the whole truck, Im swapping in the tranny and everything. If I have to move the firewall thats not a biggie. I havent decided yet if Im going to run an intercooler or just some meth. The meth sure would make it easier! The truck is getting 20"x10" wheels in the back with radials, I just dont see it getting enough traction to break parts

 

My.02:
I think the 12-bolt will live. In such a small/light truck, traction will be more of an issue than axle snappage. Launching hard with a 3500 pound truck is a lot easier on the drivetrain than launching hard with a 7+ thousand pound truck, IMO. My biggest concern, especially considering the 'pro touring' intent of the vehicle, is weight distribution....that rig will really want to wag it's tail around corners with all that cast iron up front and such a short wheelbase...that's why there was never a factory shortbed regular cab cummins. I would go air spring up front with some serious shocks and maybe a bed made of concrete....good luck, sounds like an awesome project!

oh, and just go non-intercooled for the sake of space. Even tuned to 250/650 at the rear wheels, the engine will just be loafing...you can always add water-meth if you need to cool things down