FSX-SE is basically no different from FSX Gold + Acceleration. If it works in one it should work in the other.
I have both so downloaded the P-51D updates & tried them in SE. This is an FS9 model & in FSX the problem is in VC View. It's easily fixed by inverting the Alpha in the texture named glass_l.bmp. (A copy of the edited file has to be pasted into each Texture folder.)
If you don't know how to do it I've attached mine. Please tell me if that fixed it. This worked for me in a short test* but there is another texture named glassX_l.bmp that might need editing in the same way. *See shot below.
I've just checked this out & there's something very odd going on here. I've discovered that the VC in the Daddy's Girl variation from Restorations pack 1 works fine without any modification. That's the one in my shot.
Please forget my earlier comments & the file in my attachment. I should have checked it out properly before uploading it. I'll let you know if I find an explanation. Apologies for wasting your time.
OK, I finally figured it out. Each package has 4 variations using 2 different MDL files. The display problem is with the VC of the model.PR version. With my trusty deerstalker & magnifying glass I discovered there are 2 missing textures in the appropriate folders. The files in the attached zip should fix the problem. It won't hurt to paste copies into all Texture folders of the P-51D.