How to generate another obsfuscated jar with Gradle

I have a mod which where I can generate separate jars for FML and for LiteLoader. Currently I have to change the the entry in build.gradle from

jar {
    from('src/main/java') { include 'assets/**' }
appendix = 'universal'
exclude 'eu/sajuk/tsdev/zebrastogglesneak/LiteModZebrasToggleSneak.class', 'litemod.json'
}

to

jar {
    from('src/main/java') { include 'assets/**' }
extension = 'litemod'
exclude 'eu/sajuk/tsdev/zebrastogglesneak/FMLZebrasToggleSneak.class', 'mcmod.info'
}

and run the build again. Is ther a way to assemble both files in one run?

I can't use the entry

task deobfJar(type: Jar) {
    from sourceSets.main.output
    appendix = 'deobf'
}

as the output has to be obsfuscated. Which of the sourceSets is reobsfuscated?

I can't use the liteloader plugin as it's not operative for MC 1.8