Not sure if grade 5 or 8 on the u-bolts, I wasn't aware of choices. I'd probably use grade 8.

I've had various u-bolts made at a local truck stop/parts place, and they have been very cheap, complete with heavy hardened washers and tall nuts.
They have the u-bolts as various straight lengths and bend them round or square or what have you as needed.

Ask around locally before paying shipping on some.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-