M62TUB44 vs M62B46 - interchangeable?

[TerminatorX5]

Hello.

I did some google search and searched this forum as well as some others, did not get a definite answer to my question...

I presently have an 2002 E53 X5 4.6iS that needs engine work, and sourcing parts is a financial nightmare, and considering a replacement M62B46 is equally nightmarrish... However, I have seen plenty of M62B44 and M62TUB44 floating around at rather affordable rates...

Besides the obvious of demoting of the beast to the regular level, is it possible to drop an M62TUB44 in place of the M62B46 engine?

If it is possible, what is involved in making sure it is working properly? Will the ECU and the rest of the brains communicate as it is, or some reprogramming must be done? are there incompatible parts? It will not be a DIY project, a professional mechanic will do the work but I wanted to be on the knowlegable side of the issue.

I know that some people pull I-6 in favor of V8s in some racing applications, thus "upgrading" the car - I just want to get the thing back on the road...

This plea is out of desperation, as my wife wants a divorce from the 4.6is and I hope to save the car's dignity instead of abandoning it somewhere under a bridge on an interstate!!!