In need of advice, we purchased another limo company to expand our clientele.

Long story short one of the vehicles we got:

2004 lincoln navigator ( krystal )

Front end was converted to springs. To be specific strutmaster springs. But it doesnt hold the weight of the vehicle. Basically making a bang whenever going over speed bumps or pot holes etc.

Question: where can I get the proper front end suspension coils or air to make it right ?