Driveshaft Difference for 14b SF and 14b FF

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

hirschdalechevy

Full Access Member
Joined
Mar 8, 2011
Posts
726
Reaction score
511
Location
norcal
First Name
rich
Truck Year
1977
Truck Model
k-30
Engine Size
454
1-ton 14bolt ff's have 40-1/2" spring perches (to the centerbolt hole) and 3/4 ton 14bolt ff's have 42-1/2" spring perches. Which means the frames are a little more narrow, which would also offset the shock mounts an inch or so.

Not to argue , but the frames are the same width for 1 ton & 3/4 ton , it's the spring hangers that are different. I have used 1 ton 14 bolt F.F. rears on two of my 1/2 ton trucks with the 40-1/2" spring perches and all I did was drill out the rivets and change the spring hangers from one truck to the other and I was good to go , shock mounts were good to go as well.
:patriot::patriot::patriot:
 

crazy4offroad

Equal Opportunity Destroyer
Joined
Jul 30, 2010
Posts
8,468
Reaction score
1,069
Location
West BY-GOD Virginia
First Name
Curt
Truck Year
1979
Truck Model
K-10
Engine Size
350/SM465/NP205
You are right, sir. Let this be a lesson to us all...DONT DRINK AND POST! :lol:
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,087
Reaction score
23,881
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
Yep, I've got 1-ton rear springs, hangers, axle, and shock mounts under the rear of my Burb. On a 1-ton, not only are the shocks inboard of the frame rails, but they are also staggered the opposite direction as the 1/2 and 3/4 tons.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,014
Reaction score
9,009
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
So is that the deal? If you use 1 ton spring hangers, the 1 ton bolts into a 3/4 or 1/2ton? Cuz I know a guy who also has a 1 ton rear end in a 3/4 ton and it bolted right in. I assumed the different measurements was probably a Dual rear wheel 1 ton used the different perch dimensions. So the perch dimensions really are different, but the difference is in the hangers???
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,087
Reaction score
23,881
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
1-tons all have the narrower perch spacing, regardless of how many wheels are back there. The difference is made up with the spring hangers, the frame rails are the same distance apart as the 1/2 and 3/4 ton.

Oh, and Crew Cab C20's basically have a 1-ton frame and rear spring hangers. That's the only situation where a 1-ton rear will swap directly into a 3/4 ton truck.
 
Last edited by a moderator:

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,014
Reaction score
9,009
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
1-tons all have the narrower perch spacing, regardless of how many wheels are back there. The difference is made up with the spring hangers, the frame rails are the same distance apart as the 1/2 and 3/4 ton.

Oh, and Crew Cab C20's basically have a 1-ton frame and rear spring hangers. That's the only situation where a 1-ton rear will swap directly into a 3/4 ton truck.

OK, makes sense. So the guy who has the 1 ton axle in his 3/4 ton, also upgraded his srpings and 1 ton hangers too then.

I was aware of the Crew Cab C20. It my understanding, there is no basically about it, 3/4 ton Crew Cab IS built on a 1 ton chassis. I'll take a guess and say probably the only difference is the spring packs ??? I'd imagine the brakes would be the same. Maybe the 3/4 ton also had smaller tires from the factory too :shrug: Just my understanding there is very very little difference in the C20 and C30 Crew Cabs.
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,087
Reaction score
23,881
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
I don't know either. I'm guessing just slightly softer springs and maybe smaller rear drums.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,014
Reaction score
9,009
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
Now, this brings me to my CUCV 14B Full Floater. I bought that disk brake converted 4.56 Detroit Locker rear end for my 3/4 ton truck. I know they call them 1.25 ton trucks or D30's, so that means my CUCV rear end isn't going to bolt into my 3/4 ton truck huh??? I'd have to have the perches moved. :yucky:

attachment.php
 

Attachments

  • mancave5.jpg
    mancave5.jpg
    72.5 KB · Views: 180
Last edited:

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,087
Reaction score
23,881
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
Well, I'll tell ya what. Since you don't want to install it anymore, I'll come and get it out of your way for you:rofl:
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,014
Reaction score
9,009
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
You prolly won't want it when I'm done pulling the disk brake kit off of it, the gears out of it and the Locker out of it to put in my other housing. I'll just transfer the guts to my 3.21 diff and freshen up the bearings, seals and reset the lash to compensate for any wear. I paid a whole $125 for that thing, I sure can't give it up. And that happens to be the dude I bought the 88 Burb off of that I just sold too, so buying that rear end was a very very good deal all said and done.
 

HotRodPC

Administrator
Staff member
Admin
Joined
Aug 29, 2010
Posts
47,014
Reaction score
9,009
Location
OKC, OK
First Name
HotRod
Truck Year
85 K20 LWB
Truck Model
Silverado
Engine Size
454 - Turbo 400 - 3.73
you the king of good deals... lol

Just gotta seek them out, and when you find them, be FAST and stay on it til you have possesion of it. That other 14b with the CUCV rear end, was FREE one off of CL. Ad said, FREE Chevy 8 bolt rear end. Its been sitting on my carport for over a year and my husband hasn't done a thing with it, so it must go now, and be gone before he gets home from work.
LMAO, I seen the ad pop up, called immediatly and left 2 emails. She called me right back, I got directions, said I'm on my way with an engine hoist be there in 20-30 minutes. I got there and the poor lady was begging me to come into her house and show her how to cancel a CL ad, cuz her dumb ass put her cell # on it ,and her phone was ringing and ringing and ringing. I kid you not it was non stop. She made me cancel the ad first before I loaded it.
LMAO, and she had deleted that email, that CL told her to keep in case she wanted to edit the ad. She was freaking out. Luckily, she hadn't emptied her trash email and I was able to recover it and cancel the ad. Its a 4.10 ratio and came with the lift blocks and the springs. I think it might be a 1 ton too, not positive.
 

Latest posts

Forum statistics

Threads
42,065
Posts
908,290
Members
33,542
Latest member
willyg
Top