If electrical is the ancient knob and tube, it may or may not be in need of work in the future.The duplex I am living in now was built in 1880, but all plumbing and electrical had been updated in the last decade so those systems are as good as in a new build.

You'll find a lot of multis built in the late 1890s to the 1930s and those come with all the usual physical plant precautions - knob & tube, cedar pilings, ancient plumbing, etc.RPR is a good tool, but more than that, I'd be looking at Trulia's crime heat maps and MLS rental histories. 

What I love about them the most is that the hosts always have the beginner investors in mind, so it doesn't sound like ancient Greek to newbies.

Has ancient HVAC system (that would be replaced at a later date), interiors are good (enough for renters).

Contemplating oil to gas conversion of four ancient oil boilers in a 4-plex where leases stipulate that new tenants receive their tanks 'full' must have auto-delivery contract and leave tank full upon lease expiration.

Find some ancient cottages and start mail-blasting the owners.

I just finished with "The Richest Man in Babylon" which I would highly recommend to listen to in the car if you can get past all the ancient names!

There is some hideous vinyl in the kitchen & dining and the water heater is ancient, but the HVAC is brand new.

These ancient furnaces aren't as energy efficient as today's models, and you don't want one to give out right away.b) Make sure that the furnace filters are changed on a regular basis.  

It hasn't sold purely because the owners live 5 hours away and are trying to sell in FSBO and the pictures online are still from when his 90 year old parents lived there with ancient furniture and decor. it makes a 2010 house look like its from the 60's.Again, I really appreciate your time to give me your two cents.Rental Income (1400 monthly)Less: Operating expense ($1786 taxes/insurance, 6%vacancy, water, trash, repairs, capex)Less: Mortgage payments (0% interest $850 monthly)CashFlow$16800- 5064-10200+1536