[VAC] Replacement Furnace

["Bruce Coonrod" <coonrod@xxxxxxxx>]

    I need to replace the original Suburban furnace in my '68 Tradewind. I'm
still considering alternative heat sources, including a catalytic heater.
    But if I do replace it with another forced air furnace, what should I
look for? How do the air intake and exhaust work with a replacement? What
are the difficulties of going from a round duct on new furnaces to my square
ducts?
    In other words, which furnace might require the least conversion?

Bruce Coonrod
WBCCI 15920
VAC