Air strut / air spring / shock advice

2013 L405 Range Rover 5.0SC with 175,000 Km.

Before I spend $$$ on new front struts, rear shocks, and rear airbags (could maybe skip rear bags) does anyone have any advice to test if the dampening properties are gone?

I know the OEM method is to remove the front struts, turn them upside down, and see if oil leaks out the air line hole. Rear shock would be similar in removing and seeing how easily they compress.

I am trying to keep from removing the struts and shocks, finding them faulty, reinstalling them, ordering and waiting for parts to arrive. Ordering before, not needing them, and sending them back is a waste of money.

None of my airbags are leaking or lose air overnight. The vehicle doesn’t seem planted on anything but smooth pavement. Lots of ‘pinging’ and ‘clunks’ over loose, broken, or uneven pavement.

I have already replaced the:

Front and rear sway bar bushings
Front and rear sway bar end links
Front lower forward control arms
Front lower rearward control arms
Engine mounts Dan. 🇨🇦 2013 L405 5.0 SCV8

I swapped over to my 20” all-terrains from the 22” summers. That helped with tires noise (not a problem) but didn’t do much for the suspension noise.

I ordered two OEM BWI struts from Island 4x4 and replacement hardware from JLR. More to come… Dan. 🇨🇦 2013 L405 5.0 SCV8