I have read thru this and i did even respond, but quickly deleted my post due to it not being relevant to what the OP asked.
To answer your question, based solely on my observations, the short answer is MAYBE....
Long answer, and I promise I won't mention that other brand that you aren't asking about
The aftermarket is a strange animal and as folks have mentioned before, there are a number of joints that show up in boxes with lots of different names that have the infamous "555" stamp on them. The price and quality of the materials and fit and finish may vary. Anything that is aftermarket generally has been reverse engineered from a OEM part. The fit of the parts typically are similar, because they have to be, but that does not mean that the materials used to construct the part are up to OE standard, the rubber boots for example may be less durable, or the steel used for the ball and stud may be inferior to OE spec, but only slightly.
Also, as with a number of parts in the market, part "X" and part "Y" could be made on the exact same assembly line, but part "X" gets built with higher quality components or may have higher QC standards than part "Y", which is where the added cost comes from.
Specifically speaking to your question, I would suspect that the RB joint that you are speaking of specifically is likely the same joint that is being sold by NAPA under their "Master Ride Chassis" Product line. The NAPA premium that you are speaking of is likely from their "NAPA Chassis Parts" product line, then I also show a "Altrom" Product line that they advertise as the "Sankei 555 Brand" that are $155 which is well above what you should pay for a LBJ IMHO.
Besides all that, when ordering from Rockauto or any online vendor of aftermarket parts, they are mostly all third party vendors and you are going to be at the mercy of whatever someone put in the box that is on the distributor shelf.
In the end you are the one making the final decision and based on what I have observed, there is a good possibility that whatever aftermarket joint you purchase, there is a high possibility that you will get a 555 casting mark on it, but as has been stated a few places, it is just that, a casting mark, and the machining of the balls and sockets, internal tolerances, rubber and grease are all going to be based on the price point of the joint you choose. If you pay more, you should expect more, but if you pay less, you should expect less.
To further validate my point about QC and better components then go to the NAPA website and read the two warranties that come with the two lower priced joints. The Master Ride comes with a 12,000 mile limited warranty and the NAPA Chassis comes with a limited lifetime warranty for "the period of service life recommended by the vehicle or equipment manufacturer".
What that tells me is that they are expecting the Master Ride to go 12,000 miles, but they are not holding their breathes after that. Meaning the NAPA Chassis series is built with tighter tolerances and higher quality components.
So in the end you may get a joint that when placed side by side with any other joint may look exactly the same, down to the casting marks, fit and finish, but to truly know what you have in your hand, you would probably have to destroy the joint so you could examine each component with a micrometer to determine if it is truly an equivalent.
Good Luck in whatever your final decision is.
Also, FWIW, I have only heard of one, maybe 2 documented LBJ failures on 2wd rigs.
ound:
