I am putting together a modded survival LP and was wondering, since some of my mods don't go past 1.5.2, would mods from 1.6.4 work in 1.5.2? If this helps, the mod only adds blocks and there is nothing that affects world gen. The mod is the Trampoline Mod by VoidsWrath.
My suggestion would be to test it out and see if things break. Sometimes you will need to download a previous version of the mod that works for 1.5.2.