As a single member LLC you are taxed as a sole prop on a Sch C so for you nothing will change if you get an EIN for an LLC ... as to why they require it ... probably so that they can avoid the IRS employee rules and thus avoid paying you as an employee... this is an end run around the rules : https://www.irs.gov/taxtopics/tc762
Since they will have you drive their truck and they will pay for all the truck expenses you are technically an employee and should be paid as such. They should be paying 1/2 the SE taxes, pay workman's comp, a per diem and provide you with health insurance.
