Square or round leaf spring U-bolts… What trucks used them?

[derotoreut]

I posted this in the suspension forum, but couldn't get anyone to bite on this one. I'm sorry for listing this again, but I'm trying to get an answer.

I see that some of the trucks used square rear leaf spring U-bolts and some used round U-bolts. in the 67-72 truck years, what were used and when? I'm curious because I'm installing a Skyjacker lift on a '70 K10 and they sent me square spring mounting bolts, but my rear axle was installed with round U-bolts.

The first picture shows the new U-bolts for both the front (rounded) and rear (square). The rear U-bolts on my truck are round as can be seen by 2nd pic.

[hugger6933]

I would think being with the axle under the spring that would call for the rounded type U bolt. The real difference will be made on the type of U bolt retainer and how it mounts. The trucks like the 88-98 had the spring on top of the axles [as most do] but the U bolt went in from the top across the spring and into a semi circle shaped retainer at the bottom making a square top make sense. [more sense than this post after I have typed it out]

[Bigdav160]

I have round U-bolts for the front axle and square for the rear. It the OE setup.

Rounded U-bolts for the rear is a popular upgrade and, I believe, used on later (73+) trucks.

[derotoreut]

What's confusing to me then is that the Skyjacker hardware kit (C224AS) sent to me contains square rear U-bolts and says it covers 73-87 Chev. I ordered it for my '70 K10, which has round U-bolts. I thought they were original, but could have been changed for all I know. There is also a kit (C125A) that apparently covers 67-87 Chev that contains round U-bolts.

I'm not so worried about getting the rounded U-bolts to fit my truck. I know I can buy them if need be. It's just confusing to me as to what trucks had square rear U-bolts and what ones used the rounded U-bolts. My service manual even shows pictures of square U-bolts.

[ERASER5]

I just depends on how you want to mount you springs. "U" bolts put the bolt around the axel and the plate on the spring. The "Square" bolts put the bolt around the spring and the plate on the axel.

My '70 GMC originally was spring over axel with the square u-bolt over the spring with a formed plate under the axel. The formed plate held mud and rusted my u-bolt away. I found spring plates at the junk yard (?? Cherokee) and replaced the square u-bolts with "U" u-bolts(AZone lift block kit.. did not use the block). Now the bolts point up and there is no mud pack to rust down my bolts.

[imjeff]

My 72 has square u-bolts. One of the retainers broke. It looked like a cast piece. I replaced it with a newer suburban retainer, but wish I had went with the round setup and probably will. I like having the threads pointing up rather than dragging across rocks.

Jeff

[derotoreut]

Originally Posted by imjeff

My 72 has square u-bolts. One of the retainers broke. It looked like a cast piece. I replaced it with a newer suburban retainer, but wish I had went with the round setup and probably will. I like having the threads pointing up rather than dragging across rocks.

Jeff

I agree! I prefer them mounted up. Looks cleaner.

[derotoreut]

Well I found out that the hardware listing in the Skyjacker instructions is incorrect. I contacted them today and they told me it wasn't right. So… it looks like Bigdav160 is right. They told me that 73 and up use the round U-bolts mounted from bottom up, and the 67-72's use the square U-bolts mounted from top down. If this is wrong I'm sure someone will chime in.

Based on this, it looks like someone did a U-bolt flip on my '70 k10 because they were round from bottom up. So now it looks like I have to buy new round U-bolts because Skyjacker said the stock OE configuration for my truck is square U-bolts, and that's what they supplied. No big deal because I prefer it that way. I'll just buy some new round ones and list the square ones in the For Sale section.