Ive got a customer who wants to add A/C to her trailer. She has a coil in the furnace, but will have to replace to 13 seer coil to match the condenser. Question is this, supply house first says that new coil will fit in the furnace, then I call back and they say that it might not fit but the feedback they are getting is that if I notch out the top lip of the case it will slide in and work. I guess Im asking if any of you guys have had to do this to any of the coleman units. The model number of the unit is Mod: 7836-730. Yes I know it is a old unit and would be better to replace but unit looks in good shape and of course she says she cant afford hole new system. Anyway appreciate any info on this situation.