Retirement tax questions

Thank you for providing that information but I do want to make sure I have this right so after I left that company they changed who handles their 401K and the new company information that I got the distribution from is below and next to the Distribution Code 1 on my 1099-R form is IRA/SEP/Simple is checked so was it still a 401K or had it changed into an IRA? Then how do I complete my taxes to make sure I do get the most back I can? I don't want to complete them incorrectly and then have more headaches later on and my extension request has been approved. 

TIN: 75-3182674

MATRIX TRUST COMPANY

ONEAMERICA

P.O. BOX 52129

PHOENIX, AZ [removed]

 

Thank you for helping me with this.