Dan Air only used two main types of (extremely noisy) rear engined aircraft – the twin engine BAC One-Eleven and the triple engine Boeing 727.
Orient Thai uses two variants of the MD 80 series, the MD-81 and the MD-82; the MD 80 series are essentially a second generation stretched version of the old DC 9.
The BAC One-Eleven and the DC 9 were often mistaken for each other due to their similar appearance
Details of the Orient Thai fleet from:
http://www.planespotters.net/Airline/Or ... i-Airlines