Apologies to all.
It's been so long since I posted this and have not revisited the forum since then. I can't remember, honestly, what the original post was. But it looks like I might have been in a really short temper that day and was irritated by the first few responses. Must have edited out the original message in disgust.
In any case. It's months later. The 300lb behemoth rests safely (from us) 'neath many more tons of scrap steel at Padnos reclamation. I dismantled it and loaded it in the pickup myself. Yes, there were a couple of 10x12x1/4 inch asbestos pads sandwiching the burner/plenum mounts. I soaked the crap out of them in clear acrylic paint and let it harden overnight. Then extremely carefully, with fully rated respirator, triple bagged them and properly disposed of them at a local hazardous waste site.
When dismantling I discovered that the exhaust, routed up the chimney, ran directly through the return air plenum on its way. Could have been to avoid having to route another pipe outside of the furnace on its way to the exit, or it might have been some mediocre attempt at recouping a little bit of heat on its way out. In any case, there was a 1.5 inch round hole rusted through this pipe right in middle of the fresh air return plenum. That had to contribute to the winter blahs a bit in this house.
Now the 18 year old furnace I'm replacing this with was indeed free.
It's in excellent condition and the efficiency sticker indicates 92.8. My old furnace was probably under 60 percent. The date I determined by the spec sheet inside the bottom panel. a-1995 at the middle bottom. I believe it was installed new approx four to five years after that date according to the friend who gave it to me. He installed geothermal on his 80 acre ranch and had this under a tarpaulin in the garage.
So under the heading of "nothing to lose" if it gives me poor service or poops out too early I will have made the space and provided the ductwork to simply slide-in a brand new identically dimensioned Rheem/Ruud in just a few hours. The old one should net 20 bucks in scrap.
These are the drawings I'm emailing around for estimates. The gray portions exist. The blue are needed to join the new furnace to supply and return boxes above. The 6" wide cabinet next to the furnace holds a 25x20x5 filter element. I was going to replace it with a thinner version for replacement cost sake (those fat ones are scary expensive) till I shopped a bit and discovered that they aren't bad if you buy a dozen at once and just store them.
Of four contacted, only one has gotten back to me yet with a price of 251.80. I neglected to ask what gauge he's using. Another place asked me which I required, 22 or 24? For three small pieces I ought to just go 22ga. Can't be much more in material cost.
Anyone know if these components can be purchased online, custom made, shipped flat, for less expense? Only one site I discovered did just that, but when contacted they did not sell retail.
So there's the (much) fuller version of the original post. My apologies again for leaving it to seed earlier.
I've thrown all this out there for comment. I've never done any HVAC. I have a nephew who worked in HVAC for ten years who will help me assemble the pieces and seams. Don't know if he's certified for inspections but I suppose that is a must for something like this for insurance purposes.