I'm hoping for some Guru insight onto why Frontier shocks are not compatible with the R51.

I've spent a lot of time looking the differences up, and it seems to come down to one pivotal clue:

Frontier Extended Bumper Stop Yes
Pathfinder Extended Bumper Stop No

For Monroe and others, this is the singular and only difference between the two.
For the life of me, I can not figure out what this actually means.

When I think of bump stop, I think of the control arms stops, but this seems to indicate some specific design differences, internal to the strut?

Monroe, though, states specifically in the strut configuration that it is a "bump stop unit".

For each shock, the size, the extended and compressed lengths are the same, and the stroke of each is the same. Even the springs when purchased after market are the same.

Even the strut service pack #'s are the same..

So where does the "bump stop unit" come into play here in the strut assembly.
And most importantly, why it is stipulated / needed?

Hoping someone can straighten my mind out on this subject.

Thank you for any help.

Since you're referencing to springs and shocks/struts. I'm going to assume you're talking about the front here. There is no difference between the Frontier, Pathfinder, or Xterra when it comes to the front suspension. They're all the same and all interchangeable. I don't own a Frontier to know what the differences are between the rear shocks though.

Sorry, it was for the front struts.

Thanks for the quick reply. Just an oddity.

for anyone that wanted to know:

Here are the "new" Sachs D41 shocks, combined with springs from a 2022 Frontier with 5k.
Got these from Car-part.com, strut assemblies, shipped, for the price of just the new OEM springs from Nissan.

*SACHs is now supplying shocks for Nissan, and they also are available for the R51 on Rockauto.

Comparison photo of the differences between ACDelco Professional 45H0431 Front Coil Spring Set that I installed in 2019, and the Nissan ones.

AC Delco are now shit and rusting - and basically - I should have never installed them in first place.

So, I have swapped out my front springs to Nissan and continued to use the Bils, as the Nissan ones have the 8 coils that match the rear. The difference in ride quality is immediate on the less coiled springs. No difference in handling to me.

I have the Sachs struts, on the side, for the future.
Bils are have a bit longer body than OEM, but the springs are the same height.