Replacement heaters

[JimC]

Does anyone know a source of accurate info for replacement heaters? The information I've found out there is a little confusing.

This site: https://janitrol.aero/southwind-aircraft-heaters/
says we're not eligible for the AMOC and if we want to ditch the AD, we have to get a replacement heater. The existing heater can't be upgraded.

This page: https://janitrol.aero/aircraft-heate...n-information/
says we need an I-2500 series, part number 42D79-1(IS)

This page: https://hartzell.aero/pma/cd11050-1/
also lists the part number as 42D79, replaced under PMA (not an STC.)

This page: http://www.aeroinstock.net/wp-conten...tzellcabin.pdf
says that not too long ago (2014) they were selling for $3300.

But Aircraft Spruce (https://www.aircraftspruce.com/pages...heatersnew.php)
says the 42D79-1(IS) is an I-3500 series, and it's selling for $5961. (Click on part number "07-18420" to get the details.)

There's a 42D79 for sale on eBay (https://www.ebay.com/itm/Janitrol-Co...-/123089334133)
but it's the older B2030 model and *is* subject to the AD (https://www.federalregister.gov/docu...s-models-b1500). It's the same part number, but a different model. It can be upgraded to the I-series according to this: https://janitrol.aero/wp-content/upl...er-Upgrade.pdf

Does anyone have any clarity here on the best way to get a heater installed that isn't subject to the AD?