The Stovebolt Site Forums The Shop Area Engine Shop 38 Pickup differential swap

Hey guys, a geezer here.

Bail me out. I bought a 38 automobile, complete, running gear from a guy who was rodding, because in 1959 sometime, my father in-law had a junk yard. AND. Having no money and resurrecting a 38 chev P.U. which was in its last resting place, He allowed me to scavenge the yard for anything that would work. So O the rear end of a 50 Chev was a start, as 15 inch tires were always available and 5 lug rims. Some other time I will relate how we pulled all this off, front and back.

My question, will the 38 car rearend slip under the pickup. I have another 37 pu front and rear, in addition to the front and rear from the car(knee action). I bought the "knee" job for the hubs primarily. The problem with the 37 pu rear end, I started to rebuild it about 20 years ago and its exposed mostly surface rust.

I don't wallow around underneath as good as I used to, what is your .50 cents worth on a swap????

Gene
Here is my little ditty;

"you can't catch fish if your line ain't in the water"

I'd say it's time to get the measurin' stick and compare them, including the spring mounts..

Hey stick
Will you hold one end so I get a correct measure?
I want to know if the ratio and bearings etc are compatible. If I can take the "guts" and interchange in the other housing, or use the entire housing without disassembly. Driveshaft length, axle length.

When I get home this weekend, I'll check the interchange books I have access to..If yer gonna swap the complete units, a tape measure will tell
you if the housings are the same physical size..If the width and spring perches are the same, it should work ok..the car ratio will be higher than the truck, so should give you better road speed...

I do road construction so only get home on weekends..have wifi access where my rv is parked..

If you can even put a 38 car rear axle under a 38 pickup truck or the insides of a 38 car rear axle into a 38 truck housing, you will be going from a 4.11 to 1 rear axle ration to a 3.73 to 1 rear axle ratio.

That will net you about 5 mph more speed at the same RPM.

Joe

Wheezer Below are several books that have helped me. I suggest the one you will find most helpful for what you want to do is the factory assembly manual. Also check with Amazon.com for other books that will help. They are worth every penny you spend on them.

• How to restore your Chevrolet Pickup by Tom Brownell
• Chevy Truck Shop Manual
• Chevy Truck Factory Assembly Manual
• The Glove Box Operating Manual
• Bed Restoration Manual for Early Chevrolet and GMC Pickup Truck

OK Guys now we are getting close!
That is a 50 (car)rearend presently, however, the springs mount in front of the axle, so the wheels don't line up in the center of the wheel well. The 38 car rearend also has a front spring mount, but what are the other specifics. You GUYS would never believe what we rubed up to get where I'm at! AND it was my regular driver on I 25 for 10 years or more. Now I would like to make it look and run decent.
Thanks guys I have ordered a couple of books.
PS
by the way I have a 36 Ply and a 59 DeSoto restored.both trophy winners at Nat shows.

Looks like your on the right path there Wheezer. Let us know how it turns out and send pictures.

I just had a Hot Flash ZZZZZ
What if I were to just leave the 49 housing(as it already has the spring brackets welded in the right place) and change the torque tube and differential. OOPS that won't work its not centered in the fender, thats why I want change.
Is the car springs shorter??? Longer ???

Hey 6slicksoverTx Oh thats 6cylinderoverTX
I was running a 37 4 speed,& Bell housing with a modified clutch fork to accomadate the throwout bearing,to eliminate the carbon throwout, with a TRUCK clutch. This allowed me to start out in 3rd gear by slipping the clutch and stay with traffic from a stop using the car rearend. If I had to use 2nd on a hill it was slow going with that non synchro trans to catch back up with traffic. The same clutch plate and throwout is still intact, and non of this problem had anything to do with why I quit driving it.

Hey big chevy3600
Thanks I have purchased a couple of books, my experience is the book misses a lot of important facts that a hands on shade tree guy has discovered. In regards to the bed its pretty simple and every thing but the basic cab and frame has been replaced with parts off of 3 different trucks at one tim or the other. The first time I was rearended, by a damned lawyer, nuff said. Had to replace the bed.

Say Stick
regarding that 38 pu/car swap, what if anything did you find out?
I'm looking for the easy "cheap" way out. Well there is no cheap way at todays shipping handling rates.