First - I'm so glad you came back!
I'm not sure if the credit union released the truck thinking/knowing it could hold your funds for ransom. Maybe it wasn't a clean release - ?
Not uncommon when it's a debt to pay the creditor's legal fees - not necessarily fair, such as in your case.
IF the settlement sounds reasonable to you, I would take it. If, on the other hand, it doesn't, yes, I'd get another opinion. Also make sure there's an understanding about what will or won't be reported to the credit reporting services. You don't want this as a blemish on your record.
Would I get a second opinion? Yes, I would. Too many twists and turns in this situation.
On the other hand if you are 100% confident in your Lawyer, I wouldn't get that second opinion.
(I work in the profession, had my own situation some years ago, first Attorney told me I would 100% lose, not a chance I could win. I believe I was right, retained another Attorney, WON 100%. Sometimes it's a matter of where they are coming from.)