These are brand new chrome plated brass banjo fitting so you can use a SPG on your double hose.  You must have a long yoke to use the banjo fitting.  If you are not sure what style of yoke you have email me some photos and I can tell you.  I also have a limited number of long yokes for sale for both two and single stages.  Please check the site for availability.  This banjo is 3/8 threads to work with your vintage pressure gauge.  If you want to use a modern gauge using 7/16 an additional adapter is needed.

Price $49.00 plus $3.00 shipping.