Hello OLD_DAD, both versions of the Hs-126 use different hooks for the weapon options and their carriers, the T piece is for the smoke cannister if memory serves, I made that for the earlier version that did not have the ability to make smoke and used a fuel tank with it as a placeholder.
Dreamk later sent me the update with his altered weapon options and to retain some of those changes I had to alter some of the hooks, one of those changed was the T piece to go with his new fully working smoke dispenser and a few other things, if you mix and match parts from both versions then you might reintroduce some earlier hook alterations hence why this particular part is the wrong way around, not only that but originally I used some stock bombs that were replaced with those Dreamk made especially, again if mixing parts you could be putting back the original game hooks.
The best option is to use one or other aircraft and the bomb packs recommended for it, depending on if some of those parts you changed belonged to gear items please remember some things changed between 4.10 and 4.12, myself and Dreamk made things to use in a 4.12 environment so all the hooks work for us with the various bomb combinations.
Take care and be safe.
Wishing you all the very best, Pete.