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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Topic started by: uptonogood99 on May 17, 2010, 03:01:41 pm

Title: swapping in a dual wheel rear end into a k20
Post by: uptonogood99 on May 17, 2010, 03:01:41 pm

Hi, I am swapping a duel 14 bolt from a 73 c30 into a 87 k20. I have found that the spring hangers need to be the narrow ones. The problem that I'm having is, according to gm parts the hangers for a c30 and k30 are different, and I don't know if the c30 rear springs will work. If anyone has tried any of this, or knows the difference in the hangers, it would really help me out.  Thanks,Dave

Title: Re: swapping in a dual wheel rear end into a k20
Post by: Mr Diesel on May 19, 2010, 08:43:51 pm

I have a C30 and a K30. Tomorrow I will go out and compare them.

Title: Re: swapping in a dual wheel rear end into a k20
Post by: 78 Chevyrado on May 20, 2010, 08:28:14 am

I may be wrong, but i think the difference in the C30 and K30 hangars is the height.  The k30 ones are taller than the C30 ones.

Title: Re: swapping in a dual wheel rear end into a k20
Post by: fbody on May 20, 2010, 09:08:42 am

post some pics of work-in-progress when u can.  diff driveshaft right.. due to size of the diff, longer pinion ( i think). other than hangers any other issues?  good project though.

Title: Re: swapping in a dual wheel rear end into a k20
Post by: Mr Diesel on May 21, 2010, 07:15:16 am

Just measured them. The K30 hangers (that bolt to the frame) are about 2" longer than the C30 hangers.

The extra 2" just gives it that much more ride height. The springs measure the same width, so I don't see why you couldn't use C30 springs with K30 hangers.

Title: Re: swapping in a dual wheel rear end into a k20
Post by: big trucker on May 21, 2010, 04:57:23 pm

the springs are longer on a one ton but you can use your k20 full setup the problem i had was a dually has a narrower frame you will have to move the spring seats on the rearend out

Title: Re: swapping in a dual wheel rear end into a k20
Post by: uptonogood99 on May 25, 2010, 07:53:50 am

 I have found the difference between the c30 and k20. 1st 73 to 78 use the same spring hangers on all 30 series trucks, the k have blocks under the springs to level the truck. On 79 thru 87 the hangers are different. The c's have shorter hangers which keep the spring higher up on the frame, and the k's have longer hangers. The other thing I found is that all 30 series hangers sit 2 inches in from the frame allowing for duel wheel. On the 20 series, they are 4 inches out, because duel wheels were never an availible option. Also I found all of these hangers are still available from GM, but the supports are hard to find. I was able to get the last 2 from GM vintage parts. I will post pics soon. Thanks for the help.