Here is the tap you need when drilling and tapping your own steering box. These are usually special order items anyway, so why not get it along with your ram assist kit from Low Range Off Road and save yourself some money on the part and the shipping?
- 1/4" HSS NPT Tap, and Drill Bit sized for Tap.
Note: Beware of Low Carbon Steel taps. Using a low priced tap may cause the threads to be messed up and leave your steering box useless.