Brilliant bit of work in this agree this could be the likely source.
I had brought some aircraft capacitors for my build (when I get back to it) but this feels more likely
What model Fender is pictured above?
I’m fairly certain those are large Axial Paper Electrolytic Capacitors from a Tube Amplifier on the side of the pack, I’ve seen them on guitar amps many times before in my years. Definitely NOT “Shotgun Shells”!
This is exactly what it appears to be from my perception.