I want to put HD Bilsteins on my car.

I see them listed as two different part numbers... and at two different prices.
Are these the same part simply with different part numbers, or is there a difference and if so what is the difference?

Please help.

-Confused.

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P.S. - previously posted under a different title, but retrying with better title since the previous post go no replies

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I have a w126 (1989 420SEL) and I want to replace the rear shocks with HD Bilsteins. I am confused because I can find Bilstein part number F4-B46-0511-H0 listed as REAR HD shocks for my car, and I can also find REAR HD shocks listed as part number W0133-1612941 (Listed as Bilstein HD, OEM)

I can find the W0133... part for about $15 - $20 less than the other.

Can someone please enlighten me on the the part numbers / difference in prices.