Lowering a C20-CS Longbed

[HYPR]

Ok, I know most want to lift these 3/4 tons but that's just not me.
Looking at two vendors for Drop spindles
Performanceonline DS7187 2.5" $449.99
Gmcpauls 19722647 (Fits 71-72 C20-BO until May) 2.5” $410.00
Both claim to be American made.

Now comes the rear leaf springs which are spring over axle so using lowering blocks is out. Since I will not be towing my thoughts are to remove the two helper springs which gives me about 1". I can dial in some dampening using a set of QA1 double adjustable shocks for ride. So far all the 2.5" Lowering shackles are either made for C10s '73 or newer and POL makes the RHK7391 which offers a 3-4" drop but only made for the 73-91 C30 which according to my research is the same width spring so I am not sure why this wouldn't fit and just toss the mounting bracket. I can't seem to find anything for the '72 C20 (2.5" wide leaf spring) so I am looking for recommendations before I resort to having my son fabricate some (Fabricator) by welding up a set. I really don't wan't to go through the expense and experimentation of de-arching the springs. So any assistance would be appreciated.
Bob

[Astro-Balls]

it would be Cheaper and Easier to get Lifts for your Shoes...

[HYPR]

Originally Posted by Astro-Balls

it would be Cheaper and Easier to get Lifts for your Shoes...

Well ok, but how is that going to make my truck look cooler and easier to load my Harley in the bed? LOL!
Actually Sky from GMCPauls replied to an inquiry I posted:Hi, Bob
I'm sorry we do not have a manufacturer for these. Options we know of are remove leafs to lower loosing some load carrying capabilities, use 1/2 ton shackles by drilling them out to accept the larger diameter bolt used on the 3/4 ton shackles. This leads me to think that the only difference may be the mounting bolts and bushing diameter. If that is the case than the set for the C30 might use and even larger bolt that the C20 which would only require the use of the appropriate bushing and possibly drill the hole in the mount larger. That would be really cool. So if someone with a C30 could please give me the diameter of the spring bushings and bolts I would be grateful.
Bob

[Mike C]

I'm not a fan of pulling leaves from a spring pack other than the overload. Early Classics and DJM both offer 2 1/4" leaf spring drop shackle.

On my old C2500 I ran a drop shackle in the rear and stock height front. I pulled heavy and needed the overload.

On my '69 short step I'm running a DJM flip kit but that results in a 7" drop, which is awesome on my little truck but too much without C-notching a C2500. You can get 4" drop springs for the rear and except for the cost that is the way I would drop a C2500 if you still wanted to load it up. They would be the same springs as for a C1500 but you could add overload air bags which would be slick.

[1971 for fun]

I used djm sh1012c2 drop shackles and they fit great.

[HYPR]

Originally Posted by Mike C

I'm not a fan of pulling leaves from a spring pack other than the overload. Early Classics and DJM both offer 2 1/4" leaf spring drop shackle.

On my old C2500 I ran a drop shackle in the rear and stock height front. I pulled heavy and needed the overload.

On my '69 short step I'm running a DJM flip kit but that results in a 7" drop, which is awesome on my little truck but too much without C-notching a C2500. You can get 4" drop springs for the rear and except for the cost that is the way I would drop a C2500 if you still wanted to load it up. They would be the same springs as for a C1500 but you could add overload air bags which would be slick.

Ok, I thought I missed something but after checking both sites, yep same as all the others, Nothing specific for the 1972 C20. The springs, like the C30 are 2.5" with 1.5" eyelet bushings and 9/16" bolts which is why, unless I am missing something like the drop distance position of the Hanger anything for the '73 C30 should fit.
I'm used to having to mod parts since I have a '56 210.
Isn't Hot Rodding fun?

[rjs53]

I may have missed it but why not do an axle flip, and put the springs on the bottom of the axle? You'll more than likely have to C notch it.

[Mike C]

Originally Posted by HYPR

Ok, I thought I missed something but after checking both sites, yep same as all the others, Nothing specific for the 1972 C20. The springs, like the C30 are 2.5" with 1.5" eyelet bushings and 9/16" bolts which is why, unless I am missing something like the drop distance position of the Hanger anything for the '73 C30 should fit.
I'm used to having to mod parts since I have a '56 210.
Isn't Hot Rodding fun?

The springs on your C20 should be 2.25” wide. If you have springs that are 2.5” wide, something else is going on with your truck. The 69-72 4x4 trucks and Longhorns had 2.5” wide springs, but the C10/C20 trucks use a 2.25” wide spring.

[HYPR]

Doing some more research based on GmcPaul's response I decided to see what spring bushing a '72 C20 uses and what a '73 C30 uses. According to SDtrucksprings.com all 2.5 wide springs use a 3" wide shackle and the variance is the bolt size. The C30 uses a 9/16" bolt. The C20 also does. In addition they both call for the same bushing part number and same OEM style shackle on their website: Crossover Part Numbers
330-148A, SE-434

Vehicle Applications
Years: 1969, 1970, 1971, 1972
Models: C&P 20/30 2wd, K10/20 4wd
Years: 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982
So unless I am missing something the drop shackle for the C30 should work just not using the Shackle hanger and stick with the one on the C20. Worst case is needing to remove the C20 Hanger by grinding off the rivets and installing the one from the kit.

[CG]

There are a lot of dropped 3/4 tons on this site. They will chime in as they see your post or you could do a search.