what is the difference between the optima yellow top group D34 and the D34/78? i own a honda civic and it calls for an D51R...which is discontinued and no longer in stock at the factorys warehouse. Instead, im wanting to try an D34/78 as a replacement as a drop in since thats what the autozones and pepboys here carrys. im willing to remove the battery tray and bend the tie down latch a little. i need to figure out which of these 2 sizes are smaller?