Shady is correct the KLM F100s were TAY620-15 with triple AHRS, the F70s had twin IRS, KLM later aquired 5 used F100s with 650-15 engines with triple IRS. All F100s have been retired and only the F70s remain in service.
I am informed that this airframe was ex BMI so probably did have triple IRS, not that that makes a huge difference given the challenges to the crew on the day with primative NDB equipment and terrain issues.