[5l1v3r]

First, thank you very much ss120396 for your research.
I contacted the dealer. When it was all said and done, this is the equipment matching list (amongst other things):

American Standard - Platinum Series 4 Ton, 20 SEER, R410A Variable Speed Heat Pump Unit, 208-230/1/60 4A6V0X48A1000A
American Standard - Platinum Series, 4 Ton Variable Speed Multi-Position Air Handler, R410A, 208-230/1/60 TAMXB0C48V41DA
UX360 Link Smart Thermostat THUI2360A200U
SC360 System Controller TSYS2C60A2VVU
Electric Heater, 20kW, Breaker, 24V Control, 1 Ph BAYEABC20BK1
Supply Duct Flange C BAYSUPFLGCA
Single Point Power Entry Kit BAYSPEKT200A
Internal Condensate Switch Kit BAYICSKIT01A
Low Voltage Conduit Entry Kit BAYLVKIT100A

AHRI 19.25 SEER
All this seemed compatible. The lead time is a few months, but my current system still works meantime.
He offered to upgrade the 22 year old vapor line from 3/4" to 7/8" (AS recommended size) but said it was probably was not worth the cost and he'd just clean it.
There is an option for the American Standard AccuClean Whole Home Air Cleaner AFD235CLAH000C, but it was kinda pricey...

So, this thread resulted in a complete rework of the quote. He said that AS/Trane already notified him of the incompatibility and just never got around to reworking the quote.

 

[5l1v3r]

FYI, these are the part numbers they put in the quote, so I put them in this original post.

ss120396: Thank you, I'll drop the Thermostat concern knowing it'll be compatible now.
mgenious33: Because of your post, it spun off a question in my mind....

I cannot determine the new "X" model number for the condenser, so does anyone of you professionals know what it would be for the American Standard 4-ton 48k BTU XV20i "X" series heat pumps? It's not anywhere online nor any manuals about it available anyway for me to lookup. I'll take that information to my dealer via email and follow up about it. Maybe they know, maybe they don't. Maybe they assume, maybe they don't. Most likely, Trane/AS won't be shipping any previous generation off the line from what mgenious33 is saying. Basically, logistical back-ordering and inventory is more of a pro thing plus their experience, I can only ask educated questions and learn... Thanks everyone! I can tell you folks really love this trade!