I'm installing a new garage goor. The tracks end between two trusses. Should I put a piece of wood in between the trusses or use punched angle iron, or any other suggestions.
Probably both---whatever will give you good firm support for the tracks.
A stout 2 X 6 can be bolted connecting the two trusses, then the steel angle brackets can be tied to that to connect the tracks to the 2 X 6.
Make sure you leave enough room for the electric door lifter (if you will use one)---they are always positioned in the same area as the 2 X 6.
JacktheShack's suggestions are good ones.
That's how mine end as well .... I just used a single angle bracket ... the key was not to have it too long and to use 2 lag screws into the lumber.
Hope this helps. :)