Called HR and this is how they calculated the pays:
Separation: (Base + APB) / 260 (#of working days in a year) * 5 = Weekly pay
Weekly Pay * 6 = 6 weeks separation pay you received
SAAB payout is calculated the same way, except they do not include APB
Do not look at your regular bi-weekly pay stub to determine your weekly pay for the above. Regular pays are calculated differently: Regular bi-weekly pay = Base/24.
If you also received a smaller check, it is the SPP refund since Feb 19. In the SPP pay stub you see some amount remaining in the "A Stock Period-to-Date". This is what you contributed beginning of the year until Feb 19, when SPPs were purchased. So, you own stocks for that amount.