I bought pressure gauge stuff from Amazon
EDGE INDUSTRIAL Brass REDUCING... https://www.amazon.com/dp/B07D23JS2X?ref=ppx_pop_mob_ap_share
Unijin P251 Series 2.5" Dial, Oil... https://www.amazon.com/dp/B086HGJ5TD?ref=ppx_pop_mob_ap_share
https://www.amazon.com/dp/B07D23JS2X?ref_=cm_sw_r_cp_ud_dp_PR4SP92RQ3P6XE2XJ4B0
this is the coupling i used