How to get a car with bad credit even though i pay my car payment all the time?

my grandmother signed for a mortgage for a House for my dad 4 yrs ago and she bought a car 2 and a half yrs ago at the time of her buying the car she had a credit score of 670 her payments are $169 a month and the bank she pays to is m%26amp;t bank she never missed a car payment was never late with one she was always on time last year my dads house that my grandmother signed for went into for-closer my dad and grandmother ain't talking anymore so nothing was done about the house her credit went down the drain so to speak and she still owes $5600 on her car but wants a new one if she sells her car gets enough to pay it off she wants to buy a 1998 chevy blazer for $4600 with a $1000 down payment her payments a month would be $75.68 a month for 5 years if she went back to m%26amp;t bank my question is would they accept the loan? under the fact that she has had a loan with them for a car and was never late and always on time with the payments even though she has bad credit (would they do it because of there previous business with my grandmother that they never had any problems)How to get a car with bad credit even though i pay my car payment all the time?
If she co-signed, the house payment falls on her since your dad didn't pay for it. Yes, it affects her credit rating. That's why you NEVER co-sign for someone. Even the Bible says not to accept responsibility for other's debts.

Also, more than likely, she will not get a 1998 vehicle financed for more than 3 years.

It sucks, but that's life.