we have a 1964 mobile and the inside ceiling is sagging. we don't have alot of money, so we figured that we could run 16th boards across the original truss and screw them up to it and then re-pannel over the original ceiling. the truss isn't broken, so what is the BEST way to do this? Should we use L braces as well?

please have your mobile home leveled first and then do what you planned. the same thing occured with my 1973 mobile home and all we did was run 1/2 by 2 inch pieces of lumber the width of the 16 foot ceiling and screwed them into the beams. that has been 20 years ago and they are still holding. use 2 inch wood screws.