[A/S] A few Overlander questions

[SHMossLanding@xxxxxxx]

Well, I done most of the fun stuff on our rig.  It down to the serious stuff. 
 I don't feel safe using the 30+ year old furnace. But in checking around, it 
seems the new replacemant units are around $500 or so.  Any suggestions on 
alternative source for heating up the unit if we need to.  We are in 
Monterey, CA at sea level now, but if we travel, at some point we will need 
heat.  Any ideas?

       Also, I asked this before, got the answer but lost it when my computer 
crashed. I want to replace the split rims on our trailer, the size of tires 
on it now are 700r15.  The question is, are these the right size and what 
wheels can I get at the junkyard that will be a suitable replacement?
      
       To have the wheel bearings repacked, is this something that must be 
done at an RV dealer,  or is it something any local mechanic can do?
                         Thanks,
                               Chuck & Lynn
                               1965 Overlander