I assume that when you say 4.2 you mean EAP 4.2 not AS 4.2.0.GA, right? I assume this because you mention 4.3, and there is an EAP 4.3, but not an AS 4.3.
I also assume that you are pulling the JAR file out of the JBoss Maven reposiotyr because the JAR files, as they come with EAP, do not have version numbers attached.
I compared the JAR files in EAP 4.2 to EAP 4.3 (well, I looked only at jbossts-common.jar, I assume the others will follow the same pattern). In most of the JAR file the manifest.mf file gives the version number. Not so for the JBossTS JARs - the only version information they contains is the EAP version:
Based on this I would not know that the one for 4.2 is equivalent to the jbossts-common-4.2.3-SP5.jar you mentioned.
Finally, what are you doing that you need these files? Or at least any specific version? The JTA spec has not changed in years (as far as I know) and thus the APIs should be the same in all versions . In other words, you can compile with any version (if you really need to). And I assume that you are not packing the files in your app but rather using the ones the come with EAP 4.3.
I'm not sure if this helps. But if you do need the exact version number to update your Maven builds then you will have to ask the JBossTS team since they insist on not providing version numbers within their manifests (the other JBoss projects tend to provide such information).