I'll just wait then, or if I can solve it myself, I will

I have not tried to force you or anyone else into changing anything at all, just wanted to see if it was possible, and when I found out that quick and dirty way of converting textures, I mentioned it.
It later proved that there is a technique that makes textures show equally correct in FS9 and FSX, so when using that from the beginning, there will be no problems.
(The "Backwards compatibility" mentioned from MS, is probably meant to be:
If all rules set up for eg. repainting, ai-scheduling, airport tampering etc. etc. etc has been followed then it would be backwards compatible.
MS can't be blamed not to be backwards compatible with something that do not follow their way of doing it by the letter.
As almost anything can be done in several ways and still give the same result (or looks like it), MS can not ensure forward and/or backward compatibility unless rules are strictly followed.
There is no problem in converting FS2004 default aircraft to FSX....they have been made using MS own rules, not amazingly detailed or extremely excellent I give you that, but they are easyly converted. HJG's 707 and DM's VC10 for instance are completely a nother ball game, but it does not take much to convert them to FSX either. At least all of the things that has been done "by the book" then of caoure there will be several "specialities" there will be diffult to cinvert, but mind you NOT impossible.
I realize that this might sound like a rant, rest assure, it isn't, not at all.
When I get started I just can't stop, and I do have the small problem of doing translation as I write a long so bear with me

You (Tony) and the others from HJG has made a great job. You have tested in FS9, and only committed your-self to support FS9, there is nothing wrong here at all. All us busy-body's trying things out in FSX can't expect you to clean up everything we find. We must do somethings our self if we want to use the "finer arts". At least for a while still

FSX does, when it loads up after a new aircraft has been installed, a scan of any newly added files. When it find an FS9 or even older version of eg. a GAU, it prompts you to either accept this gau or not, it even prompts you for a one session only trust or not. If this prompt comes up, you can be sure that this MIGHT work in FSX but not for certainty (hence the warning), so whether it is this gau or something completely different that is causing CTD I cannot say.
If at anytime there should be made a 707-late.gau compiled with tools from the FSX-SDK, that possibility would be removed. But it is at your own discretion if you want to use it or not.
Well I better stop now so someone can have a go at me :-)
OK, shoot... :gigle: