I would like to know if a 55' Olds upper control arm will fit the 54'? The 54' is a knee action shock which I would like to move away from if possible and go with a cartridge shock. Has anyone done this or is it even possible? Let me know what you see or done. Thanks!

 

Beautiful 54!
Unfortunately I cannot give you an exact answer if 55' upper arms will work.
I can say I have a 53 with the same style lever action shocks and am not a fan either.
I have looked and am considering having a custom bracket added from the lower arms and the frame and adding some modern style shocks to the front suspension.
I think that would make for a much firmer ride, although that wont be stock.