I have noticed that on most Midwest Express DC-9's that the seat belt signs are on the ceiling above the aisle (look at the picture I took) (copy and paste the address)
On 3 other DC-9's they are under the overhead compartments. On the MD-80's they are also under the overhead compartments.
Also on some -10's they are only in the front. by row 1 on the ceiling in the aisle. They are the ones that say
" NO SMOKING " "FASTEN SEAT BELTS"
Thanks for the replies!!!