I used to do a lot of work on the Philaadelphia Mainline and there are loads of emergency generators in the basements of the mansions mostly running on natural gas. Most are Hemis but I've come across more than one big block Chevy and several four and six cylinder Fords on small 100 amp units. When you can get them, they are always mint and maintained over the years religiously. There is a Hemi powered siren still on the roof of a building in Ardmore. Not a fire house so I suspect it was cold war era nuclear warning for Philadelphia. Ir has been left with the sheetmetal off on the roof so it's pretty much trash.