Hello guys looking I am looking for some advice on the best Dual Fuel systems out on the market. I am currently utilizing a 14 year old Heil Gas Pack 5 ton cooling and 125,000 btu heat converted to propane (natural gas is unavailable) I live in the Middle TN area. I see that Rheem/Carrier/Trane and some others have units available. I am sure that there are some differences in these not sure other than a SS heat exchanger what would be the most important. I do not see a 90% package unit so far, most of these package units seem to be 80% not sure why that is maybe you guys do? Any information will be greatly appreciated the current unit is working fine but propane costs have risen dramatically in the last year or so and look to be pushing upward again. I think a nice efficient dual fuel unit might make sense for me maybe.