What are these shocks?

Hello, trying to identify a pair of nice used rear shocks.
40mm OD body, 13mm shaft, 80mm threaded spring adjustment, 50 clicks of damping adjustment. The only number on them is 6556 on the top eye.
They were from a Harley Dyna, and once I changed the bushings, a good fit on my KZ750/4 LTD.
Bought them from a used parts dealer. They were actually the ones who found my lost cell phone! So I felt I deserved to buy something nice from them once I went to get the phone.
Any identification advice most appreciated!

That LOOKS like a Penske shock.  Might want to check there.

did a "Penske Racing shock" google search and one that looked similar showed up on Schnitz Racing website for $1500.

Fzck me gently! It was a pretty good buy for $300 Canadian then! I’ll use it!

I have a Race Tech Gold Valve kit in the front forks, so should be a nice ride. Had it professionally installed though, so no chance for error!