LS Bellhammer, LS Bellhammer GOLD, Bellhammer SEVEN, and Bellhammer LIGHT can all be used on engines and transmissions without problems. (The recommended amount to be added is 5-10% of the oil capacity.)
Differentials can also be used if they are mechanical (clutch mechanisms such as LSD, etc., not friction drive).
The catalogs of Bellhammer Seven and Bellhammer Light say that they are for gasoline engines only and cannot be used in diesel engines, but there are no problems such as DPF clogging even in diesel engines, so there is no problem if you add them. (It is stated that it is not recommended for diesel engines in order to prevent ridicule by those who have not actually used it, because it is generally said that there are many troubles with additives for diesel engines).