If you paid to have your LLC taxes done separate of your personal tax return, your LLC must either be filing as a partnership or an S-Corp.  Either way, if you mileage is related to that business, you can't claim it on your personal tax return.  

My vehicle deduction is on my personal side of taxes, it is not a LLC owned vehicle and the LLC did not pay for gas. I am paying for gas out of my own pocket for a truck in my personal name, so I need to record the miles I drove on my personal return. Where is this done?

There is no such thing as personal mileage that is deductible. Your business entity deducts business expenses. If your business is a separate entity, you must keep business and personal expenses strictly separated or the IRS can decide that you don't have a business at all. Your business must own the car.

If you have a Sole Proprietorship, then your mileage is deducted on Schedule C.

What are you talking about? I don't think you understand the question. Where do I enter mileage in TurboTax? It is my personal truck, and the LLC is a multi-member LLC so it can not be a Schedule C expense, it needs to be on the Schedule E for Unreimbursed Partner Expenses but from what I can tell there is absolutely not way to pull this up on the program. Where are Unreimbursed Partner Expenses located for Home & Business 2019?

The business did not pay me for gas, nor did the business pay for the vehicle.  The business does not have any vehicle expenses.  This would simply be the Schedule E form for Unreimbursed Partner Expenses by my understanding.

I received a 1099REC .  I don't want to start a business but I do want to deduct my mileage that I use

my truck for to get back and forth to the jobsite.  This is the only time I use my truck.

Do you mean a 1099-NEC?    Whether you realize it or not, you have already started a business.   If you are doing work and earning income on a form 1099-NEC, you are already self-employed.   In TurboTax, you enter this income on Schedule C, which is a business tax return.   So, you are in the right spot.    After you have entered all of your income, you will be given the opportunity to deduct all of your business related expenses, including your vehicles mileage.   You can only deduct mileage on a business return (other than medical and charity).

Go through the business questions, and after you have entered all of your income, you will be prompted to enter business expenses.   Here are instructions to enter all of your business expenses.   Where do I enter my self-employment business expenses, like home office, vehicle mileage, and suppli...

Some other information you may find helpful -  What's different now that I'm self-employed in 2021?

@vinny4

Very informational

The advice that you offered was very good.  Hopefully I can finish my grandson's 2021 tax return.