Options for 7 year old 4-ton HVAC with leaking coil

Hello,

I have a 4-ton Goodman HVAC (GSZ140491KF if it matters) with Heat Pump system that was installed when this home was built in 2020. Unfortunately I am not the original owner and the original owner never registered the unit, so the warranty is gone.

The unit is working perfectly fine (cools down to my desired temp with no issues) but when I had someone out to do the annual maintenance they said that the unit was 4 lbs low on refrigerant and they did a UV leak test and found that the coil is leaking.

The first company who came out gave me an estimate of $2300 to replace the Coil (labor + parts) with a 1 year warranty or $7250 to replace the entire unit with a Ducane HVAC and a 10 year warranty.

Since the unit was operating just fine and it seemed like it might be a scam during maintenance to say it needed to be replaced, I had another company come out who confirmed that the coil is leaking. However their offer was very different.

They said they could replace just the indoor portion of the HVAC (air handler and coil I guess?) for around $3200 and it would carry a 10 year warranty from Goodman on all replaced parts. It would be brand new and R410a.

I called back the other company and asked if they could do the same and they said their parts sources do not have any R410a systems even from different manufacturers.

Is the $3200 too good to be true? A 10 year warranty, staying on R410a and isn't much more expensive than the $2300 cost to replace the coil. Can someone tell me if that even sounds realistic to buy this and still get a 10 year warranty? I tried googling and could not find out if Goodman would really warranty this for 10 years.

Here is what the estimate says: "To Replace a 4-T Goodman R 410 A air handler unit; includes refrigerant and materials, with a 10 year manufacturer warranty and one year of Labor coverage."

Thanks for your help!