i used halfords black engine enamel on the block,could do same with the gear box too,there is a few colours avail,it brushes on real nice doesnt leave brush strokes.i didnt bother primeing it just did 2 coates,still looks good a year later.the more time cleanin up parts before paintin the better they wil look.drill with a wire brush works well.my block was total bare metal before paintin,hope this is sum help