Hunting Cargo Airlines (now Air Contractors) had two Electras that came from Northwest Territories Airlines and they had APUs in the rear cargo bay. I think both of these aircraft went to Atlantic at Coventry. Whether these are now with Buffalo I don't know.
When new, some Electra aircraft had air bottles mounted in the outboard nacelles that would allow one engine start. They were recharged by an hydraulic powered compressor. This took about 3 hours to re charge the bottles so was of little use to short haul operators. They were removed quite early on to save weight and as most airports had "Huffers" due to the arrival of Boeing 707s and DC-8s.