dodgec68

looking to do a possible cummins swap into an 84 4dr truck, was just wondering how much of a project it is as far as the front cross member and anything else big that would need to be changed. the work is not the problem I can do anything but would like some input before I jump into it. thanks all

ofcmarc

Swing in to the conversions forum. Plenty of swap info there. Several Crew cab conversions in there as well.

It's a pretty straight forward swap. Nearly all bolt in stuff.

https://www.dieseltruckresource.com/...play.php?f=157

simplysmn

There easier then you think once you swap the front cross member for motor pretty much everything bolt's back in If you need more info feel free to PM me I am in the process of doing my second truck .

Val

Trebor

I'm also doing an 80's 2WD gas to 4WD diesel crew cab short bed conversion. I'm also open for any questions that you may have.

Free89W350

Seems like a popular swap I am going to be doing a 85 4dr 8' 2wd to a 4wd 4dr 8'. Take a look in the "conversions" section there is alot of good and usefull info in there with some great write ups and pics.

jesussaves

as far as wiring, does everyone use the cummins dash and wiring harness??

simplysmn

Yes makes it much easier it's basicly plug n play that way

Trooperthorn

check out the blogs in my signature. Other than 2wd to 4wd, I have crossed most of the bridges.

jesussaves

do people swap out the axles as well? Are the 60's stong enough?

wannadiesel

Depends on what you are going to do with the truck.

simplysmn

the front 60 is fine but what I put in the rear is a corp 14 bolt very strong axle and easy to find froma 80's chevy truck

jesussaves

is it possible to just put a crew cab on the diesel frame? how hard would that be?? I just heard the axles and frame on the 93s are alot stronger

simplysmn

Yes you could but you would have to extend the frame and change the mount's around plus you would have to do alot of rewelding .As for stronger how are they stronger the frames that I have seen are the same This is from my experience of doing several swap's over the last couple yr's

jesussaves

Official info from Mysteryman

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The frames from 72 threw 93 are basically the same at a glance but quite different if you look closely..

The 8" (some were 7.5") frame was used on all the cab/chassis models. It was also used on all the 1 ton pickups and select 3/4 ton trucks..

Most of the 3/4 ton and all of the half ton's used the smaller 6" center frame.

The 1st gen diesels 89,90,91.0 250, 3/4 ton used used the 6" frame but it was a bit heavier than the earlier gas version. You could order the 8" frame
if desired but most were called single wheel 350's rather than 250's

89,90,91.0 350, 1 tons used the taller 7.5 " to 8" frame. The 8" was a bit heavier than the earlier gas version..

In 91.5 the 8" frame was updated and is heavier than all the rest that came before it... This is hard to see with the naked eye. But quite obvious on the blueprints. It was updated and the 6" frame was discontinued due to breakage problems... in conclusion.....
All 91.5, 92 and 93's 250's and 350 diesels used the SAME frame ...

The exceptions.....2wd verses 4wd....The frames are the same except for the front cross member's and spring hangers....

Converting a 2wd frame to a 4wd frame is rather easy assuming that you have the 4wd engine cross member and 4 spring hangers...


Converting a 4wd frame to a 2wd frame is a whole lot of work !!!!! You have
to change the front cross member and the engine cross member.. Weld in the motor mounts. Mount the upper control arm brackets.... None of the holes will be pre drilled for you. You will have to drill them all yourself.. The tolerance for these holes is .125 (1/8") on center .. If you miss the mark you may never get it to take a front end alignment or track properly...
I would not recommend doing a 4wd to 2wd frame conversion to a novice
or back yard mechanic..

One last note..... If you need to replace an 89,90 or 91.0 6" 250 diesel frame. And if you can not locate a diesel frame.. You can use an early 7.5" 300 gas frame.. All the holes will line up for the most part...

Be sure to measure the wheelbase of the doner frame you buy...
Trucks that were sold as "cab/chassis" have longer frames than Pickup trucks.

And dually rear axles out of "cab/chassis" trucks are NARROWER than the dually rears out of pickup trucks..

Dually rears out of "cab/chassis" CAN be used in most cases in single wheel pickup trucks.. You may need to change the gears to get highway speeds with the diesel.. 3.55 to 1 ratio is the best choice for all around use when using stock size tires.

I hope this answers all the frame questions

ADMOPARMAN

I wanted some clarification on your post... Do you mean swap the front cross member for the 2 to 4 wd conversion or gas to cummins?? I thought the engine member was the same gas to cummins so I just wanted to make sure so I didn't get a surprise later!