First up try using Australasian sites rather than American ones for correct information.
The UBCD325P2 has been discontinued in Australia and New Zealand, nothing has replaced it. The UBCD436PT is an entirely different model not a replacement.
Two versions of the 325 were released in Australia. The BCD325P2-AU and the UBCD325P2. The first version cannot be upgrade with DMR or NXDN. The UBCD325P2 can via the Uniden Australia upgrade website. Select the UBCD325P2 from the appropriate drop down list, it is the first one on that list. Before purchasing confirm that it is a UBCD325P2, the U is critical as it the lack of -AU after the model number.
In case you have some issues locating the aforementioned upgrade page, it can be found here:
Scanner Upgrade - Uniden
Uniden NZ is not part of the Uniden company, but an authorised agency, like Avera in Europe. It is advisable to use the Uniden Australia part of the website for detailed product information. Select the Kangaroo rather than the Silver Fern in the top right corner of the page.