If you have a bypass oil filter, it (the oil pressure gauge) is T'eed to the line to the filter. If you don't(many do not) it is connected to the fitting that would have gone to the filter. Step 12 on this page( I know not helping): http://chevy.oldcarmanualproject.com/shop/1947truck/47ctsm0619.htm
So, many thanks to tcleaderman for his picture. That little tiny line below the line to the oil distributer fitting.


Steve H