I hated selling those straps or U-bolts,it was always a crap shoot as far as getting the right ones the first time...
They do go by u-joint size,but no catalog I knew of ever had a vehicle listing in them for the straps,just the u-joints,at most you'd be lucky if they had a page in the back of the catalog telling you which strap or u-bolt matched up with a particular u-joint...
It's one of those parts the listing often says "match up with the original".which is not easy if you never had any!..