![]() The 138 (white face) and the 139 (black face tachs) that are readily available. The 243959 tach has a different lighting method that is pretty cool. The 959 tach uses an LED to light the entire dial in a sort of neon blue. You have to do a little extra wiring but not enough to amount to much. If you want to peruse the instructions that come with the DS243959 tach you can do so by clicking here or you can follow my instructions which are much more clear, certainly more colorful and slightly more entertaining. ![]() | Page 1 | Page 2 | Page 3 | Page 4 | |