I never put units in attics. They don't belong there. This one was already here so I had to work with what I had.

I am not real sure what I took out of this attic. AC only.
Starting from the back it went,
Plenum, 24x30
Electronic air cleaner,
Plenum, 40x14
Plenum, 48x12
Plenum, 28x32
Slab coil,
Modular blower, 60's Bard.
It was 18 feet long from the return plenum to supply flange.
Must have been use whatever you have in the shop job? For some reason one plenum had a humidifier and a 5kw heater in it...

Hard to get any pics. Media filter is over the top of the attic access. All the metal duct has duct liner in it. I did go back and cover it all with insulation. Definitely not my best work.